On the Basement of Canadian Greenstone Belts
The elucidation of the nature of the crust which originally underlay and delimited Archean volcanic-sedimentary greenstone belts is essential for the under-standing of the early Precambrian crustal record - and through it of early terrestrial evolution. Stratigraphic evidence from the Pilbara and Yi...
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Geological Association of Canada
1978
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ftuninewbrunojs:oai:ojs.journals.lib.unb.ca:article/3061 2023-05-15T17:01:50+02:00 On the Basement of Canadian Greenstone Belts Gilkson, A. Y. 1978-03-03 application/pdf https://journals.lib.unb.ca/index.php/GC/article/view/3061 eng eng Geological Association of Canada https://journals.lib.unb.ca/index.php/GC/article/view/3061/3578 https://journals.lib.unb.ca/index.php/GC/article/view/3061 Copyright (c) 2015 Geoscience Canada Geoscience Canada; Volume 5, Number 1 (1978) 1911-4850 0315-0941 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion research-article 1978 ftuninewbrunojs 2022-07-11T11:47:09Z The elucidation of the nature of the crust which originally underlay and delimited Archean volcanic-sedimentary greenstone belts is essential for the under-standing of the early Precambrian crustal record - and through it of early terrestrial evolution. Stratigraphic evidence from the Pilbara and Yilgarn cratons in Western Australia is consistent with data from the eastern Transvaal, Rhodesia and southern India, suggesting a fundamental dichotomy of major greenstone sequences. Two assemblages are recognized, including: 1 ) early greenstones which predate, and occur as xenoliths within, the isotopically oldest granites in each craton, and 2) late greenstones, which overlie the early greenstones through major paraconfor-mities accompanied by thick chert and acid volcanic units, and may in places overlap the early granites unconformably. The early granites typically consist of tonalite and granodiorite whose geochemical and isotopic parameters indicate derivation from parental basic materials. In this article, the possible relevance of these observations to the question of granite-greenstone relations in the Canadian Precambrian Shield is considered, with particular attention to the Archean crustal foundation of Keewatin (Abitibi) and Yellowknife greenstone belts. Article in Journal/Newspaper Keewatin Yellowknife University of New Brunswick: Centre for Digital Scholarship Journals Yellowknife |
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Open Polar |
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University of New Brunswick: Centre for Digital Scholarship Journals |
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ftuninewbrunojs |
language |
English |
description |
The elucidation of the nature of the crust which originally underlay and delimited Archean volcanic-sedimentary greenstone belts is essential for the under-standing of the early Precambrian crustal record - and through it of early terrestrial evolution. Stratigraphic evidence from the Pilbara and Yilgarn cratons in Western Australia is consistent with data from the eastern Transvaal, Rhodesia and southern India, suggesting a fundamental dichotomy of major greenstone sequences. Two assemblages are recognized, including: 1 ) early greenstones which predate, and occur as xenoliths within, the isotopically oldest granites in each craton, and 2) late greenstones, which overlie the early greenstones through major paraconfor-mities accompanied by thick chert and acid volcanic units, and may in places overlap the early granites unconformably. The early granites typically consist of tonalite and granodiorite whose geochemical and isotopic parameters indicate derivation from parental basic materials. In this article, the possible relevance of these observations to the question of granite-greenstone relations in the Canadian Precambrian Shield is considered, with particular attention to the Archean crustal foundation of Keewatin (Abitibi) and Yellowknife greenstone belts. |
format |
Article in Journal/Newspaper |
author |
Gilkson, A. Y. |
spellingShingle |
Gilkson, A. Y. On the Basement of Canadian Greenstone Belts |
author_facet |
Gilkson, A. Y. |
author_sort |
Gilkson, A. Y. |
title |
On the Basement of Canadian Greenstone Belts |
title_short |
On the Basement of Canadian Greenstone Belts |
title_full |
On the Basement of Canadian Greenstone Belts |
title_fullStr |
On the Basement of Canadian Greenstone Belts |
title_full_unstemmed |
On the Basement of Canadian Greenstone Belts |
title_sort |
on the basement of canadian greenstone belts |
publisher |
Geological Association of Canada |
publishDate |
1978 |
url |
https://journals.lib.unb.ca/index.php/GC/article/view/3061 |
geographic |
Yellowknife |
geographic_facet |
Yellowknife |
genre |
Keewatin Yellowknife |
genre_facet |
Keewatin Yellowknife |
op_source |
Geoscience Canada; Volume 5, Number 1 (1978) 1911-4850 0315-0941 |
op_relation |
https://journals.lib.unb.ca/index.php/GC/article/view/3061/3578 https://journals.lib.unb.ca/index.php/GC/article/view/3061 |
op_rights |
Copyright (c) 2015 Geoscience Canada |
_version_ |
1766055017731588096 |