Microfacies and microstructures of subglacial and deglacial sediments from the Pingualuit Crater Lake (Ungava Peninsula, Canada)
The Pingualuit Crater (Ungava Peninsula, Canada) hosts a freshwater basin in which a subglacial lake subsisted under the Laurentide Ice Sheet during the last glacial period. Microfacies and microstructures of a 9 m long sediment core are presented to discuss the depositional environment of deformed...
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crcansciencepubl:10.1139/cjes-2014-0041 2023-12-17T10:30:36+01:00 Microfacies and microstructures of subglacial and deglacial sediments from the Pingualuit Crater Lake (Ungava Peninsula, Canada) Guyard, Hervé Francus, Pierre St-Onge, Guillaume Hausmann, Sonja Pienitz, Reinhard Fisher, Timothy 2014 http://dx.doi.org/10.1139/cjes-2014-0041 http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjes-2014-0041 http://www.nrcresearchpress.com/doi/pdf/10.1139/cjes-2014-0041 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 51, issue 12, page 1084-1096 ISSN 0008-4077 1480-3313 General Earth and Planetary Sciences journal-article 2014 crcansciencepubl https://doi.org/10.1139/cjes-2014-0041 2023-11-19T13:39:29Z The Pingualuit Crater (Ungava Peninsula, Canada) hosts a freshwater basin in which a subglacial lake subsisted under the Laurentide Ice Sheet during the last glacial period. Microfacies and microstructures of a 9 m long sediment core are presented to discuss the depositional environment of deformed glacigenic and postglacial sequences deposited in the deep basin of the lake. Five distinct lithofacies are characterized. The range of glacial microstructures observed in the lower facies (Facies IV) reveals that high stress level occurred outside the crater during the formation of this diamicton released by the ablation of debris-rich basal glacier ice in an ice contact subglacial–proglacial lacustrine environment. The overlying subaqueous and glacigenic sediment gravity flow (Facies IIIb) is associated with a temporary absence of ice cover over the coring site, and likely results from the efflux plume and the associated suspension sedimentation produced during the retreat of the ice margin. Then, the finely laminated (<1–2 mm) and normally graded meltout silts (Facies IIIa) containing dropstones and load cast features suggest underflows in an unstable ice marginal lacustrine environment hydrologically separated from the retreating glacier but containing floating glacial ice blocks. Microstructures within occasional diamictic layers indicate sudden meltout deposits from these drifting ice blocks. The above finer-grained sediments (Facies Ib) lack typical glacial microstructures, marking the onset of postglacial organic sedimentation. These postglacial sediments are affected by post-depositional deformations due to an overlying rotational slide (Facies II) that may have perturbed the associated environmental record. Article in Journal/Newspaper glacier* Ice Sheet Ungava peninsula Canadian Science Publishing (via Crossref) Canada Crater Lake ENVELOPE(-60.667,-60.667,-62.983,-62.983) Ungava Peninsula ENVELOPE(-73.999,-73.999,60.000,60.000) Canadian Journal of Earth Sciences 51 12 1084 1096 |
institution |
Open Polar |
collection |
Canadian Science Publishing (via Crossref) |
op_collection_id |
crcansciencepubl |
language |
English |
topic |
General Earth and Planetary Sciences |
spellingShingle |
General Earth and Planetary Sciences Guyard, Hervé Francus, Pierre St-Onge, Guillaume Hausmann, Sonja Pienitz, Reinhard Microfacies and microstructures of subglacial and deglacial sediments from the Pingualuit Crater Lake (Ungava Peninsula, Canada) |
topic_facet |
General Earth and Planetary Sciences |
description |
The Pingualuit Crater (Ungava Peninsula, Canada) hosts a freshwater basin in which a subglacial lake subsisted under the Laurentide Ice Sheet during the last glacial period. Microfacies and microstructures of a 9 m long sediment core are presented to discuss the depositional environment of deformed glacigenic and postglacial sequences deposited in the deep basin of the lake. Five distinct lithofacies are characterized. The range of glacial microstructures observed in the lower facies (Facies IV) reveals that high stress level occurred outside the crater during the formation of this diamicton released by the ablation of debris-rich basal glacier ice in an ice contact subglacial–proglacial lacustrine environment. The overlying subaqueous and glacigenic sediment gravity flow (Facies IIIb) is associated with a temporary absence of ice cover over the coring site, and likely results from the efflux plume and the associated suspension sedimentation produced during the retreat of the ice margin. Then, the finely laminated (<1–2 mm) and normally graded meltout silts (Facies IIIa) containing dropstones and load cast features suggest underflows in an unstable ice marginal lacustrine environment hydrologically separated from the retreating glacier but containing floating glacial ice blocks. Microstructures within occasional diamictic layers indicate sudden meltout deposits from these drifting ice blocks. The above finer-grained sediments (Facies Ib) lack typical glacial microstructures, marking the onset of postglacial organic sedimentation. These postglacial sediments are affected by post-depositional deformations due to an overlying rotational slide (Facies II) that may have perturbed the associated environmental record. |
author2 |
Fisher, Timothy |
format |
Article in Journal/Newspaper |
author |
Guyard, Hervé Francus, Pierre St-Onge, Guillaume Hausmann, Sonja Pienitz, Reinhard |
author_facet |
Guyard, Hervé Francus, Pierre St-Onge, Guillaume Hausmann, Sonja Pienitz, Reinhard |
author_sort |
Guyard, Hervé |
title |
Microfacies and microstructures of subglacial and deglacial sediments from the Pingualuit Crater Lake (Ungava Peninsula, Canada) |
title_short |
Microfacies and microstructures of subglacial and deglacial sediments from the Pingualuit Crater Lake (Ungava Peninsula, Canada) |
title_full |
Microfacies and microstructures of subglacial and deglacial sediments from the Pingualuit Crater Lake (Ungava Peninsula, Canada) |
title_fullStr |
Microfacies and microstructures of subglacial and deglacial sediments from the Pingualuit Crater Lake (Ungava Peninsula, Canada) |
title_full_unstemmed |
Microfacies and microstructures of subglacial and deglacial sediments from the Pingualuit Crater Lake (Ungava Peninsula, Canada) |
title_sort |
microfacies and microstructures of subglacial and deglacial sediments from the pingualuit crater lake (ungava peninsula, canada) |
publisher |
Canadian Science Publishing |
publishDate |
2014 |
url |
http://dx.doi.org/10.1139/cjes-2014-0041 http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjes-2014-0041 http://www.nrcresearchpress.com/doi/pdf/10.1139/cjes-2014-0041 |
long_lat |
ENVELOPE(-60.667,-60.667,-62.983,-62.983) ENVELOPE(-73.999,-73.999,60.000,60.000) |
geographic |
Canada Crater Lake Ungava Peninsula |
geographic_facet |
Canada Crater Lake Ungava Peninsula |
genre |
glacier* Ice Sheet Ungava peninsula |
genre_facet |
glacier* Ice Sheet Ungava peninsula |
op_source |
Canadian Journal of Earth Sciences volume 51, issue 12, page 1084-1096 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/cjes-2014-0041 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
51 |
container_issue |
12 |
container_start_page |
1084 |
op_container_end_page |
1096 |
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1785583575911890944 |