Evidence for Stagnation of the Harvard Sublobe (Lake Michigan Lobe) in Northeastern Illinois, U.S.A., from 24 000 to 17 600 BP and Subsequent Tundra-Like Ice-Marginal Paleoenvironments from 17 600 to 15 700 BP
Glacial deposits of the last glaciation associated with the Harvard sublobe (Lake Michigan lobe) in northeastern Illinois, U.S.A., occur between sediment with dateable organics. The lower organics include fragments of Picea sp. as young as 24 000 ± 270 BP. The supraglacial organics occur sparsely in...
Published in: | Géographie physique et Quaternaire |
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Les Presses de l'Université de Montréal
2004
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Online Access: | http://id.erudit.org/iderudit/013145ar https://doi.org/10.7202/013145ar |
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fterudit:oai:erudit.org:013145ar 2023-05-15T18:09:28+02:00 Evidence for Stagnation of the Harvard Sublobe (Lake Michigan Lobe) in Northeastern Illinois, U.S.A., from 24 000 to 17 600 BP and Subsequent Tundra-Like Ice-Marginal Paleoenvironments from 17 600 to 15 700 BP Curry, Brandon B. Yansa, Catherine H. 2004 http://id.erudit.org/iderudit/013145ar https://doi.org/10.7202/013145ar en eng Les Presses de l'Université de Montréal Érudit Géographie physique et Quaternaire vol. 58 no. 2-3 (2004) http://id.erudit.org/iderudit/013145ar doi:10.7202/013145ar Tous droits réservés © Les Presses de l'Université de Montréal, 2006 text 2004 fterudit https://doi.org/10.7202/013145ar 2022-09-24T23:12:51Z Glacial deposits of the last glaciation associated with the Harvard sublobe (Lake Michigan lobe) in northeastern Illinois, U.S.A., occur between sediment with dateable organics. The lower organics include fragments of Picea sp. as young as 24 000 ± 270 BP. The supraglacial organics occur sparsely in laminated silt and fine sand in landforms that are positioned relatively high on the landscape, such as deposits from ice-walled lakes. These terrestrial organics yield ages that are 2500 to 1300 14C years older than organics at the base of sediment successions in nearby kettle basins. Basal 14C ages from four upland sites range from 17 610 ± 270 to 16 120 ± 80 BP. Our revised time-distance diagram of the Harvard sublobe now reflects a period of stagnation from 24 000 to about 17 600 BP. The supraglacial lacustrine silt yielded plant macrofossil assemblages of primarily tundra plants, including Salix herbacea and Dryas integrifolia. These plants likely grew in supraglacial and ice-marginal environments. The ostracode fauna include Cytherissa lacustris and Limnocythere friabilis. Geomorphic relations and ostracode ecology indicate that more than 17 m of ice buttressed some of the supraglacial lakes. Les sédiments glaciaires associés au sous-lobe de Harvard, dans le Nord-Est de l’Illinois, sont intercalés dans des sédiments dont la matière organique peut être datée. Des fragments de Picea sp. sont présents dans les couches sous-jacentes et remontent au plus à 24 000 ± 270 BP. La matière organique sus-jacente est disséminée dans les limons laminés et les sables fins de dépôts de lacs de barrage glaciaire perchés. Cette matière organique livre des âges 14C qui sont de 2500 à 1300 ans plus vieux que la matière organique de la base des sédiments des marmites glaciaires (kettles). Les âges 14C de quatre sites perchés vont de 17 610 ± 270 à 16 120 ± 80 BP. Notre révision du diagramme distance-temps du sous-lobe de Harvard traduit l’existence d’une période de stagnation glaciaire entre 24 000 et 17 600 BP. Le limon lacustre ... Text Salix herbacea Tundra Érudit.org (Université Montréal) Géographie physique et Quaternaire 58 2-3 305 321 |
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Open Polar |
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Érudit.org (Université Montréal) |
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fterudit |
language |
English |
description |
Glacial deposits of the last glaciation associated with the Harvard sublobe (Lake Michigan lobe) in northeastern Illinois, U.S.A., occur between sediment with dateable organics. The lower organics include fragments of Picea sp. as young as 24 000 ± 270 BP. The supraglacial organics occur sparsely in laminated silt and fine sand in landforms that are positioned relatively high on the landscape, such as deposits from ice-walled lakes. These terrestrial organics yield ages that are 2500 to 1300 14C years older than organics at the base of sediment successions in nearby kettle basins. Basal 14C ages from four upland sites range from 17 610 ± 270 to 16 120 ± 80 BP. Our revised time-distance diagram of the Harvard sublobe now reflects a period of stagnation from 24 000 to about 17 600 BP. The supraglacial lacustrine silt yielded plant macrofossil assemblages of primarily tundra plants, including Salix herbacea and Dryas integrifolia. These plants likely grew in supraglacial and ice-marginal environments. The ostracode fauna include Cytherissa lacustris and Limnocythere friabilis. Geomorphic relations and ostracode ecology indicate that more than 17 m of ice buttressed some of the supraglacial lakes. Les sédiments glaciaires associés au sous-lobe de Harvard, dans le Nord-Est de l’Illinois, sont intercalés dans des sédiments dont la matière organique peut être datée. Des fragments de Picea sp. sont présents dans les couches sous-jacentes et remontent au plus à 24 000 ± 270 BP. La matière organique sus-jacente est disséminée dans les limons laminés et les sables fins de dépôts de lacs de barrage glaciaire perchés. Cette matière organique livre des âges 14C qui sont de 2500 à 1300 ans plus vieux que la matière organique de la base des sédiments des marmites glaciaires (kettles). Les âges 14C de quatre sites perchés vont de 17 610 ± 270 à 16 120 ± 80 BP. Notre révision du diagramme distance-temps du sous-lobe de Harvard traduit l’existence d’une période de stagnation glaciaire entre 24 000 et 17 600 BP. Le limon lacustre ... |
format |
Text |
author |
Curry, Brandon B. Yansa, Catherine H. |
spellingShingle |
Curry, Brandon B. Yansa, Catherine H. Evidence for Stagnation of the Harvard Sublobe (Lake Michigan Lobe) in Northeastern Illinois, U.S.A., from 24 000 to 17 600 BP and Subsequent Tundra-Like Ice-Marginal Paleoenvironments from 17 600 to 15 700 BP |
author_facet |
Curry, Brandon B. Yansa, Catherine H. |
author_sort |
Curry, Brandon B. |
title |
Evidence for Stagnation of the Harvard Sublobe (Lake Michigan Lobe) in Northeastern Illinois, U.S.A., from 24 000 to 17 600 BP and Subsequent Tundra-Like Ice-Marginal Paleoenvironments from 17 600 to 15 700 BP |
title_short |
Evidence for Stagnation of the Harvard Sublobe (Lake Michigan Lobe) in Northeastern Illinois, U.S.A., from 24 000 to 17 600 BP and Subsequent Tundra-Like Ice-Marginal Paleoenvironments from 17 600 to 15 700 BP |
title_full |
Evidence for Stagnation of the Harvard Sublobe (Lake Michigan Lobe) in Northeastern Illinois, U.S.A., from 24 000 to 17 600 BP and Subsequent Tundra-Like Ice-Marginal Paleoenvironments from 17 600 to 15 700 BP |
title_fullStr |
Evidence for Stagnation of the Harvard Sublobe (Lake Michigan Lobe) in Northeastern Illinois, U.S.A., from 24 000 to 17 600 BP and Subsequent Tundra-Like Ice-Marginal Paleoenvironments from 17 600 to 15 700 BP |
title_full_unstemmed |
Evidence for Stagnation of the Harvard Sublobe (Lake Michigan Lobe) in Northeastern Illinois, U.S.A., from 24 000 to 17 600 BP and Subsequent Tundra-Like Ice-Marginal Paleoenvironments from 17 600 to 15 700 BP |
title_sort |
evidence for stagnation of the harvard sublobe (lake michigan lobe) in northeastern illinois, u.s.a., from 24 000 to 17 600 bp and subsequent tundra-like ice-marginal paleoenvironments from 17 600 to 15 700 bp |
publisher |
Les Presses de l'Université de Montréal |
publishDate |
2004 |
url |
http://id.erudit.org/iderudit/013145ar https://doi.org/10.7202/013145ar |
genre |
Salix herbacea Tundra |
genre_facet |
Salix herbacea Tundra |
op_relation |
Géographie physique et Quaternaire vol. 58 no. 2-3 (2004) http://id.erudit.org/iderudit/013145ar doi:10.7202/013145ar |
op_rights |
Tous droits réservés © Les Presses de l'Université de Montréal, 2006 |
op_doi |
https://doi.org/10.7202/013145ar |
container_title |
Géographie physique et Quaternaire |
container_volume |
58 |
container_issue |
2-3 |
container_start_page |
305 |
op_container_end_page |
321 |
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1766182046988763136 |