Cosmogenic 10Be ages from the Meirs and Garwood Valleys, Denton Hills, West Antarctica, suggest an absence in LGM Ice Sheet expansion
It has been hypothesised that during interglacials, thinning of the Ross Ice Shelf allowed a more open water environment with increased local precipitation. This resulted in outlet glaciers, which drain the Transantarctic Mountains and fed by the East Antarctic Ice Sheet, advancing during moist warm...
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ftansto:oai:apo-prod.ansto.gov.au:10238/8307 2023-05-15T13:36:16+02:00 Cosmogenic 10Be ages from the Meirs and Garwood Valleys, Denton Hills, West Antarctica, suggest an absence in LGM Ice Sheet expansion Fink, D Joy, K Carson, N Storey, B 2017-02-15 http://apo.ansto.gov.au/dspace/handle/10238/8307 https://www.egu2014.eu/home.html en eng EGU General Assembly Fink, D., Joy, K., Carson, N., & Storey, B. (April, 2014). Cosmogenic 10Be ages from the Meirs and Garwood Valleys, Denton Hills, West Antarctica, suggest an absence in LGM Ice Sheet expansion. Paper presented at the European Geosciences Union General Assembly 2014, Vienna, Austria, 27 April – 02 May 2014. https://www.egu2014.eu/home.html http://apo.ansto.gov.au/dspace/handle/10238/8307 Glaciers Antarctic Ocean Ice Water Quaternary period Polar regions Conference Abstract 2017 ftansto 2020-04-27T22:29:03Z It has been hypothesised that during interglacials, thinning of the Ross Ice Shelf allowed a more open water environment with increased local precipitation. This resulted in outlet glaciers, which drain the Transantarctic Mountains and fed by the East Antarctic Ice Sheet, advancing during moist warmer periods, apparently out of phase with colder arid dry periods. Significantly the ice core record during these warm periods also shows increased accumulation continent wide The geomorphology of the Denton Hills in the Royal Society Range, West Antarctica, is a result of Miocene fluvial incision reworked by subsequent glacial advances throughout the Quaternary. The Garwood and Miers glacial valleys drain ice across the Denton Hills into the Shelf, and should thus show maximum extent during interstadials. To understand the chronology of late Quaternary glaciations, 15 granitic boulders from terminal moraines were sampled for 10Be and 26Al cosmogenic dating. Obtaining reliable exposure ages of erratics within moraines that represent timing of deposition (i.e. glacial advances) is problematic in polar regions, where glacial activity is principally controlled by ice sheet dynamics. Recycling of previously exposed debris, uncertainty in provenance of glacially transported boulders and a lack of a post-depositional hydrologic process to remove previously exposed material from a valley system, leads to ambiguities in multiple exposure ages from a single coeval glacial landform. More importantly, cold-based ice advance can leave a landform unmodified resulting in young erratics deposited on bedrock that shows weathering and/or inconsistent age-altitude relationships. Primarily, inheritance becomes a difficulty in qualifying exposure ages from polar regions. Preliminary results from the Garwood and Miers Valleys indicate that glaciers in the Denton Hills had begun to retreat from their last maximum positions no later than 23-37 ka, and thus the local last glacial maximum occurred prior to the Antarctic LGM (18-22 ka). No evidence based on cosmogenic ages for post-LGM or Holocene advances were found. These results support an extensive exposure age data set from the nearby Darwin-Hatherton Glacier system that indicates an absence of EAIS expansion across the Transantarctic Mnts during the global LGM period. Conference Object Antarc* Antarctic Antarctic Ocean Antarctica Hatherton Glacier ice core Ice Sheet Ice Shelf Ross Ice Shelf West Antarctica Australian Nuclear Science and Technology Organisation: ANSTO Publications Online Antarctic Antarctic Ocean Denton Hills ENVELOPE(163.917,163.917,-78.083,-78.083) East Antarctic Ice Sheet Garwood ENVELOPE(164.283,164.283,-78.033,-78.033) Hatherton Glacier ENVELOPE(157.583,157.583,-79.917,-79.917) Miers ENVELOPE(163.850,163.850,-78.100,-78.100) Ross Ice Shelf Royal Society Range ENVELOPE(162.667,162.667,-78.167,-78.167) The Antarctic Transantarctic Mountains West Antarctica |
institution |
Open Polar |
collection |
Australian Nuclear Science and Technology Organisation: ANSTO Publications Online |
op_collection_id |
ftansto |
language |
English |
topic |
Glaciers Antarctic Ocean Ice Water Quaternary period Polar regions |
spellingShingle |
Glaciers Antarctic Ocean Ice Water Quaternary period Polar regions Fink, D Joy, K Carson, N Storey, B Cosmogenic 10Be ages from the Meirs and Garwood Valleys, Denton Hills, West Antarctica, suggest an absence in LGM Ice Sheet expansion |
topic_facet |
Glaciers Antarctic Ocean Ice Water Quaternary period Polar regions |
description |
It has been hypothesised that during interglacials, thinning of the Ross Ice Shelf allowed a more open water environment with increased local precipitation. This resulted in outlet glaciers, which drain the Transantarctic Mountains and fed by the East Antarctic Ice Sheet, advancing during moist warmer periods, apparently out of phase with colder arid dry periods. Significantly the ice core record during these warm periods also shows increased accumulation continent wide The geomorphology of the Denton Hills in the Royal Society Range, West Antarctica, is a result of Miocene fluvial incision reworked by subsequent glacial advances throughout the Quaternary. The Garwood and Miers glacial valleys drain ice across the Denton Hills into the Shelf, and should thus show maximum extent during interstadials. To understand the chronology of late Quaternary glaciations, 15 granitic boulders from terminal moraines were sampled for 10Be and 26Al cosmogenic dating. Obtaining reliable exposure ages of erratics within moraines that represent timing of deposition (i.e. glacial advances) is problematic in polar regions, where glacial activity is principally controlled by ice sheet dynamics. Recycling of previously exposed debris, uncertainty in provenance of glacially transported boulders and a lack of a post-depositional hydrologic process to remove previously exposed material from a valley system, leads to ambiguities in multiple exposure ages from a single coeval glacial landform. More importantly, cold-based ice advance can leave a landform unmodified resulting in young erratics deposited on bedrock that shows weathering and/or inconsistent age-altitude relationships. Primarily, inheritance becomes a difficulty in qualifying exposure ages from polar regions. Preliminary results from the Garwood and Miers Valleys indicate that glaciers in the Denton Hills had begun to retreat from their last maximum positions no later than 23-37 ka, and thus the local last glacial maximum occurred prior to the Antarctic LGM (18-22 ka). No evidence based on cosmogenic ages for post-LGM or Holocene advances were found. These results support an extensive exposure age data set from the nearby Darwin-Hatherton Glacier system that indicates an absence of EAIS expansion across the Transantarctic Mnts during the global LGM period. |
format |
Conference Object |
author |
Fink, D Joy, K Carson, N Storey, B |
author_facet |
Fink, D Joy, K Carson, N Storey, B |
author_sort |
Fink, D |
title |
Cosmogenic 10Be ages from the Meirs and Garwood Valleys, Denton Hills, West Antarctica, suggest an absence in LGM Ice Sheet expansion |
title_short |
Cosmogenic 10Be ages from the Meirs and Garwood Valleys, Denton Hills, West Antarctica, suggest an absence in LGM Ice Sheet expansion |
title_full |
Cosmogenic 10Be ages from the Meirs and Garwood Valleys, Denton Hills, West Antarctica, suggest an absence in LGM Ice Sheet expansion |
title_fullStr |
Cosmogenic 10Be ages from the Meirs and Garwood Valleys, Denton Hills, West Antarctica, suggest an absence in LGM Ice Sheet expansion |
title_full_unstemmed |
Cosmogenic 10Be ages from the Meirs and Garwood Valleys, Denton Hills, West Antarctica, suggest an absence in LGM Ice Sheet expansion |
title_sort |
cosmogenic 10be ages from the meirs and garwood valleys, denton hills, west antarctica, suggest an absence in lgm ice sheet expansion |
publisher |
EGU General Assembly |
publishDate |
2017 |
url |
http://apo.ansto.gov.au/dspace/handle/10238/8307 https://www.egu2014.eu/home.html |
long_lat |
ENVELOPE(163.917,163.917,-78.083,-78.083) ENVELOPE(164.283,164.283,-78.033,-78.033) ENVELOPE(157.583,157.583,-79.917,-79.917) ENVELOPE(163.850,163.850,-78.100,-78.100) ENVELOPE(162.667,162.667,-78.167,-78.167) |
geographic |
Antarctic Antarctic Ocean Denton Hills East Antarctic Ice Sheet Garwood Hatherton Glacier Miers Ross Ice Shelf Royal Society Range The Antarctic Transantarctic Mountains West Antarctica |
geographic_facet |
Antarctic Antarctic Ocean Denton Hills East Antarctic Ice Sheet Garwood Hatherton Glacier Miers Ross Ice Shelf Royal Society Range The Antarctic Transantarctic Mountains West Antarctica |
genre |
Antarc* Antarctic Antarctic Ocean Antarctica Hatherton Glacier ice core Ice Sheet Ice Shelf Ross Ice Shelf West Antarctica |
genre_facet |
Antarc* Antarctic Antarctic Ocean Antarctica Hatherton Glacier ice core Ice Sheet Ice Shelf Ross Ice Shelf West Antarctica |
op_relation |
Fink, D., Joy, K., Carson, N., & Storey, B. (April, 2014). Cosmogenic 10Be ages from the Meirs and Garwood Valleys, Denton Hills, West Antarctica, suggest an absence in LGM Ice Sheet expansion. Paper presented at the European Geosciences Union General Assembly 2014, Vienna, Austria, 27 April – 02 May 2014. https://www.egu2014.eu/home.html http://apo.ansto.gov.au/dspace/handle/10238/8307 |
_version_ |
1766076229410095104 |