Repeated advance and retreat of the East Antarctic Ice Sheet on the continental shelf during the early Pliocene warm period
Diatom analysis of a sediment core recovered at IODP Site U1358 on the continental shelf off the Adélie Coast indicated that the lower section of the core contained an assemblage dating back to the Thalassiosira innura Zone of the lower Pliocene that ranges from 4.2 to 5.12. Ma. Based on lithologica...
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ftunivutrecht:oai:dspace.library.uu.nl:1874/329921 2023-07-23T04:14:36+02:00 Repeated advance and retreat of the East Antarctic Ice Sheet on the continental shelf during the early Pliocene warm period Reinardy, B. T I Escutia, C. Iwai, M. Jimenez-Espejo, F. J. Cook, C. van de Flierdt, T. Brinkhuis, H. Marine palynology and palaeoceanography Marine Palynology 2015-03-15 application/pdf https://dspace.library.uu.nl/handle/1874/329921 en eng 0031-0182 https://dspace.library.uu.nl/handle/1874/329921 info:eu-repo/semantics/ClosedAccess East antarctic ice sheet Grounding line Micromorphology Pliocene Wilkes subglacial Basin Ecology Evolution Behavior and Systematics Palaeontology Earth-Surface Processes Oceanography Article 2015 ftunivutrecht 2023-07-02T01:39:48Z Diatom analysis of a sediment core recovered at IODP Site U1358 on the continental shelf off the Adélie Coast indicated that the lower section of the core contained an assemblage dating back to the Thalassiosira innura Zone of the lower Pliocene that ranges from 4.2 to 5.12. Ma. Based on lithological descriptions at both a macro- and micro-scale of this early Pliocene part of the core, four facies were interpreted from the diamictons representing the progressive advance and retreat of the grounding line over the site. Facies 1a and 1b contain a distinct directional signal from the orientation of the a-axis of clasts with several phases of fabric development along with both brittle and ductile deformation features that are common in sediments that have been subglacially deformed. Facies 1c and 1d are finely laminated and were deposited in open marine conditions. The four facies within the depositional model provide for the first time direct evidence for ice advancing across the shelf adjacent to the Wilkes Subglacial Basin on at least four occasions separated by three periods of open marine conditions indicating retreat of grounded ice inland of the site during a warmer than present early Pliocene. The times of open marine conditions are correlated with previous findings from the neighbouring rise sites that also indicated an oscillating ice margin. This has significant implications because firstly it suggests a dynamic East Antarctic Ice Sheet (EAIS) that is probably far more sensitive to climatic and oceanic forcing even during relatively short time periods than had previously been thought. Secondly it suggests that proxies used to interpret the advance and retreat of the grounding line from the rise can be linked with direct evidence of grounding line migration from the shelf. It also has important implications for the future behaviour and sensitivity of the EAIS under present continuing warming conditions. Together with results from the rise, this paper provides a crucial ice extent target for a new ice sheet ... Article in Journal/Newspaper Antarc* Antarctic Ice Sheet Utrecht University Repository Adélie Coast ENVELOPE(139.000,139.000,-60.000,-60.000) Antarctic East Antarctic Ice Sheet Wilkes Subglacial Basin ENVELOPE(145.000,145.000,-75.000,-75.000) |
institution |
Open Polar |
collection |
Utrecht University Repository |
op_collection_id |
ftunivutrecht |
language |
English |
topic |
East antarctic ice sheet Grounding line Micromorphology Pliocene Wilkes subglacial Basin Ecology Evolution Behavior and Systematics Palaeontology Earth-Surface Processes Oceanography |
spellingShingle |
East antarctic ice sheet Grounding line Micromorphology Pliocene Wilkes subglacial Basin Ecology Evolution Behavior and Systematics Palaeontology Earth-Surface Processes Oceanography Reinardy, B. T I Escutia, C. Iwai, M. Jimenez-Espejo, F. J. Cook, C. van de Flierdt, T. Brinkhuis, H. Repeated advance and retreat of the East Antarctic Ice Sheet on the continental shelf during the early Pliocene warm period |
topic_facet |
East antarctic ice sheet Grounding line Micromorphology Pliocene Wilkes subglacial Basin Ecology Evolution Behavior and Systematics Palaeontology Earth-Surface Processes Oceanography |
description |
Diatom analysis of a sediment core recovered at IODP Site U1358 on the continental shelf off the Adélie Coast indicated that the lower section of the core contained an assemblage dating back to the Thalassiosira innura Zone of the lower Pliocene that ranges from 4.2 to 5.12. Ma. Based on lithological descriptions at both a macro- and micro-scale of this early Pliocene part of the core, four facies were interpreted from the diamictons representing the progressive advance and retreat of the grounding line over the site. Facies 1a and 1b contain a distinct directional signal from the orientation of the a-axis of clasts with several phases of fabric development along with both brittle and ductile deformation features that are common in sediments that have been subglacially deformed. Facies 1c and 1d are finely laminated and were deposited in open marine conditions. The four facies within the depositional model provide for the first time direct evidence for ice advancing across the shelf adjacent to the Wilkes Subglacial Basin on at least four occasions separated by three periods of open marine conditions indicating retreat of grounded ice inland of the site during a warmer than present early Pliocene. The times of open marine conditions are correlated with previous findings from the neighbouring rise sites that also indicated an oscillating ice margin. This has significant implications because firstly it suggests a dynamic East Antarctic Ice Sheet (EAIS) that is probably far more sensitive to climatic and oceanic forcing even during relatively short time periods than had previously been thought. Secondly it suggests that proxies used to interpret the advance and retreat of the grounding line from the rise can be linked with direct evidence of grounding line migration from the shelf. It also has important implications for the future behaviour and sensitivity of the EAIS under present continuing warming conditions. Together with results from the rise, this paper provides a crucial ice extent target for a new ice sheet ... |
author2 |
Marine palynology and palaeoceanography Marine Palynology |
format |
Article in Journal/Newspaper |
author |
Reinardy, B. T I Escutia, C. Iwai, M. Jimenez-Espejo, F. J. Cook, C. van de Flierdt, T. Brinkhuis, H. |
author_facet |
Reinardy, B. T I Escutia, C. Iwai, M. Jimenez-Espejo, F. J. Cook, C. van de Flierdt, T. Brinkhuis, H. |
author_sort |
Reinardy, B. T I |
title |
Repeated advance and retreat of the East Antarctic Ice Sheet on the continental shelf during the early Pliocene warm period |
title_short |
Repeated advance and retreat of the East Antarctic Ice Sheet on the continental shelf during the early Pliocene warm period |
title_full |
Repeated advance and retreat of the East Antarctic Ice Sheet on the continental shelf during the early Pliocene warm period |
title_fullStr |
Repeated advance and retreat of the East Antarctic Ice Sheet on the continental shelf during the early Pliocene warm period |
title_full_unstemmed |
Repeated advance and retreat of the East Antarctic Ice Sheet on the continental shelf during the early Pliocene warm period |
title_sort |
repeated advance and retreat of the east antarctic ice sheet on the continental shelf during the early pliocene warm period |
publishDate |
2015 |
url |
https://dspace.library.uu.nl/handle/1874/329921 |
long_lat |
ENVELOPE(139.000,139.000,-60.000,-60.000) ENVELOPE(145.000,145.000,-75.000,-75.000) |
geographic |
Adélie Coast Antarctic East Antarctic Ice Sheet Wilkes Subglacial Basin |
geographic_facet |
Adélie Coast Antarctic East Antarctic Ice Sheet Wilkes Subglacial Basin |
genre |
Antarc* Antarctic Ice Sheet |
genre_facet |
Antarc* Antarctic Ice Sheet |
op_relation |
0031-0182 https://dspace.library.uu.nl/handle/1874/329921 |
op_rights |
info:eu-repo/semantics/ClosedAccess |
_version_ |
1772185961882451968 |