Towards a reconstruction of Marion Island’s glacial history
Southern Hemisphere glacial chronologies can provide valuable insights into interactions between glaciation and past climate changes. The sub-Antarctic Islands provide a valuable terrestrial record of glacial chronologies for the Southern Hemisphere, since they are unique, not only in size and topog...
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ftrhodesunivcory:vital:42581 2023-05-15T14:03:02+02:00 Towards a reconstruction of Marion Island’s glacial history Rudolph, Elizabeth 2020 236 leaves pdf http://hdl.handle.net/10353/18531 https://corycommons.ru.ac.za/vital/access/manager/Repository/vital:42581 English eng University of Fort Hare Faculty of Science and Agriculture http://hdl.handle.net/10353/18531 vital:42581 https://corycommons.ru.ac.za/vital/access/manager/Repository/vital:42581 University of Fort Hare Glacial landforms Geomorphological mapping Thesis Doctoral PhD (Geography) 2020 ftrhodesunivcory 2022-12-26T14:42:22Z Southern Hemisphere glacial chronologies can provide valuable insights into interactions between glaciation and past climate changes. The sub-Antarctic Islands provide a valuable terrestrial record of glacial chronologies for the Southern Hemisphere, since they are unique, not only in size and topography, but also in oceanic situation when compared to other continental landmasses (e.g. Antarctica or Patagonia). On sub-Antarctic Marion Island, southern Indian Ocean, the exact timing and extent of the local Last Glacial Maximum is not yet known as glacial reconstructions have mostly been based on palynological proxies and relative-age dating techniques. This study presents 29 cosmogenic 36Cl exposure ages of deglaciated bedrock surfaces and moraine deposits from Marion Island. In addition, a comprehensive glacial-geomorphological map, which in conjunction with exposure ages provide improved temporal and spatial constraints for the island’s glacial history. Results show that the ice reached a local Last Glacial Maximum before 56 ka ago and retreated, with minor stillstands, until ~17 ka. This early deglaciation left island surfaces below 850 m a.s.l. ice-free after ~19 ka, and any subsequent advances during the Late Glacial or Holocene cooling periods would have been restricted to the interior. This glacial chronology is similar to that of some other sub-Antarctic Islands (e.g. the Kerguelen archipelago, Auckland and Campbell islands, and possibly South Georgia) and a number of other Southern Hemisphere glaciers (e.g. in Patagonia and New Zealand) and adds to evidence that suggest the Southern Hemisphere was in a glacial maximum earlier than the global LGM. A combination of climatic drivers such as declining temperatures, a northward migration of oceanic fronts and the Southern Hemisphere Westerly Winds (causing precipitation changes), as well as the physiography of Marion Island, created optimal conditions for glacier growth during Marine Isotope Stage 4 (MIS 4; ~65 ka ago) instead of the global LGM in MIS 2 (~18 ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Antarctica Marion Island Rhodes University Cory: Repository Antarctic Campbell Islands ENVELOPE(-103.668,-103.668,56.984,56.984) Indian Kerguelen New Zealand Patagonia |
institution |
Open Polar |
collection |
Rhodes University Cory: Repository |
op_collection_id |
ftrhodesunivcory |
language |
English |
topic |
Glacial landforms Geomorphological mapping |
spellingShingle |
Glacial landforms Geomorphological mapping Rudolph, Elizabeth Towards a reconstruction of Marion Island’s glacial history |
topic_facet |
Glacial landforms Geomorphological mapping |
description |
Southern Hemisphere glacial chronologies can provide valuable insights into interactions between glaciation and past climate changes. The sub-Antarctic Islands provide a valuable terrestrial record of glacial chronologies for the Southern Hemisphere, since they are unique, not only in size and topography, but also in oceanic situation when compared to other continental landmasses (e.g. Antarctica or Patagonia). On sub-Antarctic Marion Island, southern Indian Ocean, the exact timing and extent of the local Last Glacial Maximum is not yet known as glacial reconstructions have mostly been based on palynological proxies and relative-age dating techniques. This study presents 29 cosmogenic 36Cl exposure ages of deglaciated bedrock surfaces and moraine deposits from Marion Island. In addition, a comprehensive glacial-geomorphological map, which in conjunction with exposure ages provide improved temporal and spatial constraints for the island’s glacial history. Results show that the ice reached a local Last Glacial Maximum before 56 ka ago and retreated, with minor stillstands, until ~17 ka. This early deglaciation left island surfaces below 850 m a.s.l. ice-free after ~19 ka, and any subsequent advances during the Late Glacial or Holocene cooling periods would have been restricted to the interior. This glacial chronology is similar to that of some other sub-Antarctic Islands (e.g. the Kerguelen archipelago, Auckland and Campbell islands, and possibly South Georgia) and a number of other Southern Hemisphere glaciers (e.g. in Patagonia and New Zealand) and adds to evidence that suggest the Southern Hemisphere was in a glacial maximum earlier than the global LGM. A combination of climatic drivers such as declining temperatures, a northward migration of oceanic fronts and the Southern Hemisphere Westerly Winds (causing precipitation changes), as well as the physiography of Marion Island, created optimal conditions for glacier growth during Marine Isotope Stage 4 (MIS 4; ~65 ka ago) instead of the global LGM in MIS 2 (~18 ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Rudolph, Elizabeth |
author_facet |
Rudolph, Elizabeth |
author_sort |
Rudolph, Elizabeth |
title |
Towards a reconstruction of Marion Island’s glacial history |
title_short |
Towards a reconstruction of Marion Island’s glacial history |
title_full |
Towards a reconstruction of Marion Island’s glacial history |
title_fullStr |
Towards a reconstruction of Marion Island’s glacial history |
title_full_unstemmed |
Towards a reconstruction of Marion Island’s glacial history |
title_sort |
towards a reconstruction of marion island’s glacial history |
publisher |
University of Fort Hare |
publishDate |
2020 |
url |
http://hdl.handle.net/10353/18531 https://corycommons.ru.ac.za/vital/access/manager/Repository/vital:42581 |
long_lat |
ENVELOPE(-103.668,-103.668,56.984,56.984) |
geographic |
Antarctic Campbell Islands Indian Kerguelen New Zealand Patagonia |
geographic_facet |
Antarctic Campbell Islands Indian Kerguelen New Zealand Patagonia |
genre |
Antarc* Antarctic Antarctica Marion Island |
genre_facet |
Antarc* Antarctic Antarctica Marion Island |
op_relation |
http://hdl.handle.net/10353/18531 vital:42581 https://corycommons.ru.ac.za/vital/access/manager/Repository/vital:42581 |
op_rights |
University of Fort Hare |
_version_ |
1766273512409923584 |