| Titre | Erosional bedforms on hard beds in mid-continent North America cut by palaeo-ice streams of the Laurentide Ice Sheet |
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| Auteur | Bukhari, S ;
Eyles, N; Paulen, R C; Akçar, N |
| Source | XXI INQUA Congress 2023, abstracts; 2023 p. 1 |
| Liens | Online - En ligne
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| Image |  |
| Année | 2023 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20220371 |
| Éditeur | INQUA |
| Réunion | XXI INQUA Congress 2023; Rome; IT; juillet 13-20, 2023 |
| Document | livre |
| Lang. | anglais |
| Media | papier; numérique; en ligne |
| Formats | pdf |
| Province | Ontario |
| SNRC | 30; 40; 41; 42D; 52A |
| Région | Great Lakes |
| Lat/Long OENS | -92.0000 -76.0000 49.0000 40.0000 |
| Sujets | erosion glaciaire; dépôts glaciaires; glaciers; établissement de modèles; Calotte glaciaire Laurentide; Bouclier Canadien; géologie des dépôts meubles/géomorphologie |
| Programme | Division de la CGC du Centre du Canada |
| Diffusé | 2023 07 19 |
| Résumé | (disponible en anglais seulement)
We evaluate the origins(s) of regionally extensive glacially scoured and megagrooved bedrock surfaces on the hard bed of the Great Lakes sector of the
Laurentide Ice Sheet in mid-continent North America, using newly available high resolution LiDAR derived data. These surfaces occur on a range of bedrock lithologies from Precambrian crystalline strata of the Canadian Shield, together with offlapping
Paleozoic shales and limestone escarpments and plains in Canada and the northern United States. Surfaces show a wide variety of streamlined bedrock morphotypes ranging from large km-scale rock drumlins and linear mega-grooves to ‘tadpole’ and
cigar-shaped spindles and more sinuous grooves, including sichelwannen and muschelbruch. We discuss the formative processes acting to cut these forms, focusing on the relative roles of sediment carried by high pressure subglacial water, direct
glacial abrasion by basal debris, and the abrasive action of a 'third layer' of overpressured sediment moving between ice and its bed and acting as an erodent layer. We highlight the regional geological and paleoglaciological context of scoured
bedrock surfaces and are able to recognize the critical roles played by enhanced erosion below fast flowing palaeo-ice streams, and varying bedrock lithology. This study emphasizes the fundamental importance of 'tectonic predesign' where Precambrian
terrane boundaries, faults and fractures, extending under offlapping sedimentary strata, control the paths of palaeo-ice streams, deep erosion of the Huron-Erie-Ontario Great Lake basins and the other large lake basins around the margins of the
Canadian Shield. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Il s'agit d'une présentation d'un étudiant à la maîtrise financé par GEM-GeoNorth sur ses recherches sur l'impact des courants de glace en
Amérique du Nord, en particulier les roches carbonatées paléozoïques qui bordent le Bouclier canadien, et le contrôle structurel des grands bassins lacustres qui s'y produisent. Ceci est une présentation étudiante. |
| GEOSCAN ID | 330936 |
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