Rb–Sr geochronology of the Archaean Maggo gneiss from the Hopedale block, Nain Province, Labrador
The Maggo gneiss, a typical grey gneiss from the Hopedale block of coastal Labrador (southern Nain Province), preserves structures of two major Archaean tectonothermal events, the Hopedalian and the younger Fiordian. Rb–Sr whole-rock analyses of four suites representing the Hopedalian event (3140 ±...
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1989
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crcansciencepubl:10.1139/e89-214 2023-12-17T10:31:21+01:00 Rb–Sr geochronology of the Archaean Maggo gneiss from the Hopedale block, Nain Province, Labrador Finn, Gregory C. 1989 http://dx.doi.org/10.1139/e89-214 http://www.nrcresearchpress.com/doi/pdf/10.1139/e89-214 fr fre Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 26, issue 12, page 2512-2522 ISSN 0008-4077 1480-3313 General Earth and Planetary Sciences journal-article 1989 crcansciencepubl https://doi.org/10.1139/e89-214 2023-11-19T13:38:11Z The Maggo gneiss, a typical grey gneiss from the Hopedale block of coastal Labrador (southern Nain Province), preserves structures of two major Archaean tectonothermal events, the Hopedalian and the younger Fiordian. Rb–Sr whole-rock analyses of four suites representing the Hopedalian event (3140 ± 95 Ma (1σ), 3125 ± 43 Ma, 3028 ± 199 Ma, and 3025 ± 163 Ma) fall within the early middle Archaean and represent a period of cratonization of the Hopedale block.Two suites with a younger Fiordian structural fabric (2899 ± 116 Ma and 2804 ± 100 Ma) fall within the late middle Archaean and are interpreted as dating a period of reworking that locally reset the Rb–Sr isotopic systematics of the Maggo gneiss. Fiordian ages were also determined from four suites (2927 ± 50 Ma, 2884 ± 86 Ma, 2854 ± 83 Ma, and 2764 ± 89 Ma) that do not display the Fiordian structural fabric, indicating that chemical and mechanical components of the Fiordian event did not occur simultaneously. Age determinations of the Fiordian do not date specific geologic events but seemingly reflect varying degrees of protracted isotopic homogenization during chemical and mineralogical reequilibration.One suite of analyses yields an age of 3305 ± 75 Ma and is interpreted as dating a pre-Hopedalian event. This older age supports field evidence as to the existence of old crust in the Hopedale block, typical also of rocks of the North Atlantic Craton. Article in Journal/Newspaper Hopedale Nain North Atlantic Canadian Science Publishing (via Crossref) Nain ENVELOPE(-61.695,-61.695,56.542,56.542) Canadian Journal of Earth Sciences 26 12 2512 2522 |
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Open Polar |
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Canadian Science Publishing (via Crossref) |
op_collection_id |
crcansciencepubl |
language |
French |
topic |
General Earth and Planetary Sciences |
spellingShingle |
General Earth and Planetary Sciences Finn, Gregory C. Rb–Sr geochronology of the Archaean Maggo gneiss from the Hopedale block, Nain Province, Labrador |
topic_facet |
General Earth and Planetary Sciences |
description |
The Maggo gneiss, a typical grey gneiss from the Hopedale block of coastal Labrador (southern Nain Province), preserves structures of two major Archaean tectonothermal events, the Hopedalian and the younger Fiordian. Rb–Sr whole-rock analyses of four suites representing the Hopedalian event (3140 ± 95 Ma (1σ), 3125 ± 43 Ma, 3028 ± 199 Ma, and 3025 ± 163 Ma) fall within the early middle Archaean and represent a period of cratonization of the Hopedale block.Two suites with a younger Fiordian structural fabric (2899 ± 116 Ma and 2804 ± 100 Ma) fall within the late middle Archaean and are interpreted as dating a period of reworking that locally reset the Rb–Sr isotopic systematics of the Maggo gneiss. Fiordian ages were also determined from four suites (2927 ± 50 Ma, 2884 ± 86 Ma, 2854 ± 83 Ma, and 2764 ± 89 Ma) that do not display the Fiordian structural fabric, indicating that chemical and mechanical components of the Fiordian event did not occur simultaneously. Age determinations of the Fiordian do not date specific geologic events but seemingly reflect varying degrees of protracted isotopic homogenization during chemical and mineralogical reequilibration.One suite of analyses yields an age of 3305 ± 75 Ma and is interpreted as dating a pre-Hopedalian event. This older age supports field evidence as to the existence of old crust in the Hopedale block, typical also of rocks of the North Atlantic Craton. |
format |
Article in Journal/Newspaper |
author |
Finn, Gregory C. |
author_facet |
Finn, Gregory C. |
author_sort |
Finn, Gregory C. |
title |
Rb–Sr geochronology of the Archaean Maggo gneiss from the Hopedale block, Nain Province, Labrador |
title_short |
Rb–Sr geochronology of the Archaean Maggo gneiss from the Hopedale block, Nain Province, Labrador |
title_full |
Rb–Sr geochronology of the Archaean Maggo gneiss from the Hopedale block, Nain Province, Labrador |
title_fullStr |
Rb–Sr geochronology of the Archaean Maggo gneiss from the Hopedale block, Nain Province, Labrador |
title_full_unstemmed |
Rb–Sr geochronology of the Archaean Maggo gneiss from the Hopedale block, Nain Province, Labrador |
title_sort |
rb–sr geochronology of the archaean maggo gneiss from the hopedale block, nain province, labrador |
publisher |
Canadian Science Publishing |
publishDate |
1989 |
url |
http://dx.doi.org/10.1139/e89-214 http://www.nrcresearchpress.com/doi/pdf/10.1139/e89-214 |
long_lat |
ENVELOPE(-61.695,-61.695,56.542,56.542) |
geographic |
Nain |
geographic_facet |
Nain |
genre |
Hopedale Nain North Atlantic |
genre_facet |
Hopedale Nain North Atlantic |
op_source |
Canadian Journal of Earth Sciences volume 26, issue 12, page 2512-2522 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e89-214 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
26 |
container_issue |
12 |
container_start_page |
2512 |
op_container_end_page |
2522 |
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1785584633874743296 |