The Omar Story: The Role of Omars in Assessing Glacial History of West-Central North America
The direction of Wisconsinan glacial dispersion of distinctive Proterozoic erratics derived from the Belcher Group in southeastern Hudson Bay is shown to have been northwestward, westward and southward for hundreds of kilometres across Hudson Bay, Northern Ontario, western Canada, and several adjoin...
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Les Presses de l'Université de Montréal
2000
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Online Access: | http://id.erudit.org/iderudit/005654ar https://doi.org/10.7202/005654ar |
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fterudit:oai:erudit.org:005654ar 2023-05-15T15:35:42+02:00 The Omar Story: The Role of Omars in Assessing Glacial History of West-Central North America Prest, Victor K. Donaldson, J. Allan Mooers, Howard D. 2000 http://id.erudit.org/iderudit/005654ar https://doi.org/10.7202/005654ar en eng Les Presses de l'Université de Montréal Érudit Géographie physique et Quaternaire vol. 54 no. 3 (2000) http://id.erudit.org/iderudit/005654ar doi:10.7202/005654ar Tous droits réservés © Les Presses de l'Université de Montréal ,2000 text 2000 fterudit https://doi.org/10.7202/005654ar 2022-09-24T23:12:16Z The direction of Wisconsinan glacial dispersion of distinctive Proterozoic erratics derived from the Belcher Group in southeastern Hudson Bay is shown to have been northwestward, westward and southward for hundreds of kilometres across Hudson Bay, Northern Ontario, western Canada, and several adjoining northern States. The most distinctive of these erratics, termed "omars", are composed of massive siliceous wacke characterized by buff-weathering calcareous concretions; these erratics were derived from the Omarolluk Formation of the Belcher Group, exposed in the Belcher Islands of eastern Hudson Bay, and probably underlying much of the southern part of this inland sea. Far less common but equally distinctive are erratics of red oolitic jasper that were derived from the Kipalu Formation of the Belcher Group. In parallel with the now widely accepted field term "omar", we introduce the term "kipalu" for such erratics of oolitic jasper. A map showing the distribution of the distinctive erratics, in relation to indicators of Wisconsinan glacier movement, provides the basis for inferring at least two discrete glaciations that produced several major ice lobes. This paper summarizes the field observations of numerous Canadian and American earth scientists, traces the evolution of thought on provenance of the distinctive erratics, and outlines the criteria for distinguishing "true" omars from erratics derived from other bedrock sources of concretion-bearing wackes. Des erratiques de roches protérozoïques du Groupe de Belcher du sud-est de la baie d'Hudson, montrant certaines caractéristiques particulières, ont été transportés vers le nord-ouest, l'ouest et le sud, sur des centaines de kilomètres au cours du Wisconsinien, à travers la baie d'Hudson, le nord de l'Ontario, jusque dans l'Ouest canadien et dans plusieurs états voisins du nord des États-Unis. Le plus abondant de ces erratiques, l'« omar », est un grauwacke silicieux et massif contenant, dans les cas d'altération, des concrétions calcaires de couleur chamois. ... Text Baie d'Hudson Belcher Islands glacier* Hudson Bay Érudit.org (Université Montréal) Baie d'Hudson ENVELOPE(-78.666,-78.666,58.417,58.417) Baie-d'Hudson ENVELOPE(-74.999,-74.999,58.500,58.500) Belcher ENVELOPE(-94.172,-94.172,57.936,57.936) Belcher Islands ENVELOPE(-79.250,-79.250,56.184,56.184) Buff ENVELOPE(-64.567,-64.567,-64.833,-64.833) Canada Hudson Hudson Bay Géographie physique et Quaternaire 54 3 257 270 |
institution |
Open Polar |
collection |
Érudit.org (Université Montréal) |
op_collection_id |
fterudit |
language |
English |
description |
The direction of Wisconsinan glacial dispersion of distinctive Proterozoic erratics derived from the Belcher Group in southeastern Hudson Bay is shown to have been northwestward, westward and southward for hundreds of kilometres across Hudson Bay, Northern Ontario, western Canada, and several adjoining northern States. The most distinctive of these erratics, termed "omars", are composed of massive siliceous wacke characterized by buff-weathering calcareous concretions; these erratics were derived from the Omarolluk Formation of the Belcher Group, exposed in the Belcher Islands of eastern Hudson Bay, and probably underlying much of the southern part of this inland sea. Far less common but equally distinctive are erratics of red oolitic jasper that were derived from the Kipalu Formation of the Belcher Group. In parallel with the now widely accepted field term "omar", we introduce the term "kipalu" for such erratics of oolitic jasper. A map showing the distribution of the distinctive erratics, in relation to indicators of Wisconsinan glacier movement, provides the basis for inferring at least two discrete glaciations that produced several major ice lobes. This paper summarizes the field observations of numerous Canadian and American earth scientists, traces the evolution of thought on provenance of the distinctive erratics, and outlines the criteria for distinguishing "true" omars from erratics derived from other bedrock sources of concretion-bearing wackes. Des erratiques de roches protérozoïques du Groupe de Belcher du sud-est de la baie d'Hudson, montrant certaines caractéristiques particulières, ont été transportés vers le nord-ouest, l'ouest et le sud, sur des centaines de kilomètres au cours du Wisconsinien, à travers la baie d'Hudson, le nord de l'Ontario, jusque dans l'Ouest canadien et dans plusieurs états voisins du nord des États-Unis. Le plus abondant de ces erratiques, l'« omar », est un grauwacke silicieux et massif contenant, dans les cas d'altération, des concrétions calcaires de couleur chamois. ... |
format |
Text |
author |
Prest, Victor K. Donaldson, J. Allan Mooers, Howard D. |
spellingShingle |
Prest, Victor K. Donaldson, J. Allan Mooers, Howard D. The Omar Story: The Role of Omars in Assessing Glacial History of West-Central North America |
author_facet |
Prest, Victor K. Donaldson, J. Allan Mooers, Howard D. |
author_sort |
Prest, Victor K. |
title |
The Omar Story: The Role of Omars in Assessing Glacial History of West-Central North America |
title_short |
The Omar Story: The Role of Omars in Assessing Glacial History of West-Central North America |
title_full |
The Omar Story: The Role of Omars in Assessing Glacial History of West-Central North America |
title_fullStr |
The Omar Story: The Role of Omars in Assessing Glacial History of West-Central North America |
title_full_unstemmed |
The Omar Story: The Role of Omars in Assessing Glacial History of West-Central North America |
title_sort |
omar story: the role of omars in assessing glacial history of west-central north america |
publisher |
Les Presses de l'Université de Montréal |
publishDate |
2000 |
url |
http://id.erudit.org/iderudit/005654ar https://doi.org/10.7202/005654ar |
long_lat |
ENVELOPE(-78.666,-78.666,58.417,58.417) ENVELOPE(-74.999,-74.999,58.500,58.500) ENVELOPE(-94.172,-94.172,57.936,57.936) ENVELOPE(-79.250,-79.250,56.184,56.184) ENVELOPE(-64.567,-64.567,-64.833,-64.833) |
geographic |
Baie d'Hudson Baie-d'Hudson Belcher Belcher Islands Buff Canada Hudson Hudson Bay |
geographic_facet |
Baie d'Hudson Baie-d'Hudson Belcher Belcher Islands Buff Canada Hudson Hudson Bay |
genre |
Baie d'Hudson Belcher Islands glacier* Hudson Bay |
genre_facet |
Baie d'Hudson Belcher Islands glacier* Hudson Bay |
op_relation |
Géographie physique et Quaternaire vol. 54 no. 3 (2000) http://id.erudit.org/iderudit/005654ar doi:10.7202/005654ar |
op_rights |
Tous droits réservés © Les Presses de l'Université de Montréal ,2000 |
op_doi |
https://doi.org/10.7202/005654ar |
container_title |
Géographie physique et Quaternaire |
container_volume |
54 |
container_issue |
3 |
container_start_page |
257 |
op_container_end_page |
270 |
_version_ |
1766366039970414592 |