Logan Medallist 1. Seeking the Suture: The Coast-Cascade Conundrum
The boundary between rocks assigned to the Intermontane superterrane in the interior of the Canadian Cordillera and those of the Insular superterrane in the westernmost Cordillera of British Columbia and southeastern Alaska lies within/along the Coast Mountains, in which is exposed the core of an or...
Published in: | Geoscience Canada |
---|---|
Main Author: | |
Format: | Text |
Language: | English |
Published: |
The Geological Association of Canada
2014
|
Subjects: | |
Online Access: | https://doi.org/10.12789/geocanj.2014.41.058 http://id.erudit.org/iderudit/1062254ar |
id |
fttriple:oai:gotriple.eu:10670/1.ii8280 |
---|---|
record_format |
openpolar |
spelling |
fttriple:oai:gotriple.eu:10670/1.ii8280 2023-05-15T18:49:04+02:00 Logan Medallist 1. Seeking the Suture: The Coast-Cascade Conundrum Monger, Jim W.H. 2014-01-01 https://doi.org/10.12789/geocanj.2014.41.058 http://id.erudit.org/iderudit/1062254ar en eng The Geological Association of Canada Érudit doi:10.12789/geocanj.2014.41.058 10670/1.ii8280 http://id.erudit.org/iderudit/1062254ar other Geoscience Canada: Journal of the Geological Association of Canada / Geoscience Canada: Journal de l’Association Géologique du Canada geo envir Text https://vocabularies.coar-repositories.org/resource_types/c_18cf/ 2014 fttriple https://doi.org/10.12789/geocanj.2014.41.058 2023-01-22T16:55:11Z The boundary between rocks assigned to the Intermontane superterrane in the interior of the Canadian Cordillera and those of the Insular superterrane in the westernmost Cordillera of British Columbia and southeastern Alaska lies within/along the Coast Mountains, in which is exposed the core of an orogen that emerged as a discrete tectonic entity between 105 and 45 million years ago. Evidence from the Coast Mountains and flanking areas indicates that parts of the Intermontane superterrane (in Stikinia and Yukon-Tanana terranes) were near those of the Insular superterrane (Wrangellia and Alexander terranes) by the Early Jurassic (~180 Ma). This timing, as well as paleobiogeographic and paleomagnetic considerations, appears to discount a recent hypothesis that proposes westward-dipping subduction beneath an intra-oceanic arc on Insular superterrane resulted in arc-continent collision and inaugurated Cordilleran orogenesis in the Late Jurassic (~146 Ma). The hypothesis also relates the subducted ocean that had separated the superterranes to a massive, faster-than-average-velocity seismic anomaly in the lower mantle below the eastern seaboard of North America. To create such an anomaly, subduction of the floor of a large ocean was needed. The only surface record of such an ocean in the interior of the Canadian Cordillera is the Cache Creek terrane, which lies within the Intermontane superterrane but is no younger than Middle Jurassic (~174 Ma). This terrane, together with the probably related Bridge River terrane in the southeastern Coast Mountains, which is as young as latest Middle Jurassic (164 Ma) and possibly as young as earliest Cretaceous (≥ 130 Ma), appear to be the only candidates in Canada for the possible surface record of the seismic anomaly. La limite entre les roches assignées au Superterrane d’intermont de l’intérieur des Cordillères canadiennes et celles du Superterrane insulaire dans la portion la plus à l’ouest de la Cordillère de Colombie-Britannique et du sud-est de l’Alaska se trouvent dans et ... Text Alaska Yukon Unknown Bridge River ENVELOPE(-137.217,-137.217,60.006,60.006) British Columbia ENVELOPE(-125.003,-125.003,54.000,54.000) Canada Yukon Geoscience Canada 41 4 379 |
institution |
Open Polar |
collection |
Unknown |
op_collection_id |
fttriple |
language |
English |
topic |
geo envir |
spellingShingle |
geo envir Monger, Jim W.H. Logan Medallist 1. Seeking the Suture: The Coast-Cascade Conundrum |
topic_facet |
geo envir |
description |
The boundary between rocks assigned to the Intermontane superterrane in the interior of the Canadian Cordillera and those of the Insular superterrane in the westernmost Cordillera of British Columbia and southeastern Alaska lies within/along the Coast Mountains, in which is exposed the core of an orogen that emerged as a discrete tectonic entity between 105 and 45 million years ago. Evidence from the Coast Mountains and flanking areas indicates that parts of the Intermontane superterrane (in Stikinia and Yukon-Tanana terranes) were near those of the Insular superterrane (Wrangellia and Alexander terranes) by the Early Jurassic (~180 Ma). This timing, as well as paleobiogeographic and paleomagnetic considerations, appears to discount a recent hypothesis that proposes westward-dipping subduction beneath an intra-oceanic arc on Insular superterrane resulted in arc-continent collision and inaugurated Cordilleran orogenesis in the Late Jurassic (~146 Ma). The hypothesis also relates the subducted ocean that had separated the superterranes to a massive, faster-than-average-velocity seismic anomaly in the lower mantle below the eastern seaboard of North America. To create such an anomaly, subduction of the floor of a large ocean was needed. The only surface record of such an ocean in the interior of the Canadian Cordillera is the Cache Creek terrane, which lies within the Intermontane superterrane but is no younger than Middle Jurassic (~174 Ma). This terrane, together with the probably related Bridge River terrane in the southeastern Coast Mountains, which is as young as latest Middle Jurassic (164 Ma) and possibly as young as earliest Cretaceous (≥ 130 Ma), appear to be the only candidates in Canada for the possible surface record of the seismic anomaly. La limite entre les roches assignées au Superterrane d’intermont de l’intérieur des Cordillères canadiennes et celles du Superterrane insulaire dans la portion la plus à l’ouest de la Cordillère de Colombie-Britannique et du sud-est de l’Alaska se trouvent dans et ... |
format |
Text |
author |
Monger, Jim W.H. |
author_facet |
Monger, Jim W.H. |
author_sort |
Monger, Jim W.H. |
title |
Logan Medallist 1. Seeking the Suture: The Coast-Cascade Conundrum |
title_short |
Logan Medallist 1. Seeking the Suture: The Coast-Cascade Conundrum |
title_full |
Logan Medallist 1. Seeking the Suture: The Coast-Cascade Conundrum |
title_fullStr |
Logan Medallist 1. Seeking the Suture: The Coast-Cascade Conundrum |
title_full_unstemmed |
Logan Medallist 1. Seeking the Suture: The Coast-Cascade Conundrum |
title_sort |
logan medallist 1. seeking the suture: the coast-cascade conundrum |
publisher |
The Geological Association of Canada |
publishDate |
2014 |
url |
https://doi.org/10.12789/geocanj.2014.41.058 http://id.erudit.org/iderudit/1062254ar |
long_lat |
ENVELOPE(-137.217,-137.217,60.006,60.006) ENVELOPE(-125.003,-125.003,54.000,54.000) |
geographic |
Bridge River British Columbia Canada Yukon |
geographic_facet |
Bridge River British Columbia Canada Yukon |
genre |
Alaska Yukon |
genre_facet |
Alaska Yukon |
op_source |
Geoscience Canada: Journal of the Geological Association of Canada / Geoscience Canada: Journal de l’Association Géologique du Canada |
op_relation |
doi:10.12789/geocanj.2014.41.058 10670/1.ii8280 http://id.erudit.org/iderudit/1062254ar |
op_rights |
other |
op_doi |
https://doi.org/10.12789/geocanj.2014.41.058 |
container_title |
Geoscience Canada |
container_volume |
41 |
container_issue |
4 |
container_start_page |
379 |
_version_ |
1766242502034063360 |