Bay of Islands and Little Port complexes, revisited: age, geochemical and isotopic evidence confirm suprasubduction-zone origin
The Bay of Islands Complex of the Humber Arm allochthon, west Newfoundland, contains the best-exposed ophiolite in the Appalachian Orogen. Associated structural slices, the Little Port and Skinner Cove complexes, also contain rocks formed in an oceanic domain, although their relationship to the Bay...
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Canadian Science Publishing
1991
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crcansciencepubl:10.1139/e91-146 2024-06-23T07:54:47+00:00 Bay of Islands and Little Port complexes, revisited: age, geochemical and isotopic evidence confirm suprasubduction-zone origin Jenner, G. A. Dunning, G. R. Malpas, J. Brown, M. Brace, T. 1991 http://dx.doi.org/10.1139/e91-146 http://www.nrcresearchpress.com/doi/pdf/10.1139/e91-146 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 28, issue 10, page 1635-1652 ISSN 0008-4077 1480-3313 journal-article 1991 crcansciencepubl https://doi.org/10.1139/e91-146 2024-06-13T04:10:51Z The Bay of Islands Complex of the Humber Arm allochthon, west Newfoundland, contains the best-exposed ophiolite in the Appalachian Orogen. Associated structural slices, the Little Port and Skinner Cove complexes, also contain rocks formed in an oceanic domain, although their relationship to the Bay of Islands Complex remains controversial.To constrain the origin of the complexes and obtain a better understanding of the geology of the Humber Arm allochthon, we have undertaken an integrated geochronological, geochemical, and isotopic study. A U/Pb zircon age of [Formula: see text] Ma for the Little Port Complex and a zircon and baddeleyite age of 484 ± 5 Ma for the Bay of Islands Complex have been obtained. Geochemical and isotopic data on trondhjemitic rocks from the two complexes indicate that petrogenetic models for these rocks must account for fundamental differences in source materials and mineralogy during differentiation. The Little Port Complex trondhjemites are characterized by initial ε Nd of −1 to +1, whereas those in the Bay of Islands have ε Nd of +6.5. Geochemical signatures in mafic and felsic volcanics of the complexes are diverse, and show a complete gradation between arc and non-arc.The Bay of Islands and Little Port complexes are not related by any form of a major mid-ocean-ridge – transform-fault model. An alternative model to explain the relationships between the two complexes interprets the Little Port as arc-related and the Bay of Islands as a suprasubduction-zone ophiolite. Article in Journal/Newspaper Newfoundland Canadian Science Publishing Skinner Cove ENVELOPE(-54.398,-54.398,49.667,49.667) Canadian Journal of Earth Sciences 28 10 1635 1652 |
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Open Polar |
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Canadian Science Publishing |
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crcansciencepubl |
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English |
description |
The Bay of Islands Complex of the Humber Arm allochthon, west Newfoundland, contains the best-exposed ophiolite in the Appalachian Orogen. Associated structural slices, the Little Port and Skinner Cove complexes, also contain rocks formed in an oceanic domain, although their relationship to the Bay of Islands Complex remains controversial.To constrain the origin of the complexes and obtain a better understanding of the geology of the Humber Arm allochthon, we have undertaken an integrated geochronological, geochemical, and isotopic study. A U/Pb zircon age of [Formula: see text] Ma for the Little Port Complex and a zircon and baddeleyite age of 484 ± 5 Ma for the Bay of Islands Complex have been obtained. Geochemical and isotopic data on trondhjemitic rocks from the two complexes indicate that petrogenetic models for these rocks must account for fundamental differences in source materials and mineralogy during differentiation. The Little Port Complex trondhjemites are characterized by initial ε Nd of −1 to +1, whereas those in the Bay of Islands have ε Nd of +6.5. Geochemical signatures in mafic and felsic volcanics of the complexes are diverse, and show a complete gradation between arc and non-arc.The Bay of Islands and Little Port complexes are not related by any form of a major mid-ocean-ridge – transform-fault model. An alternative model to explain the relationships between the two complexes interprets the Little Port as arc-related and the Bay of Islands as a suprasubduction-zone ophiolite. |
format |
Article in Journal/Newspaper |
author |
Jenner, G. A. Dunning, G. R. Malpas, J. Brown, M. Brace, T. |
spellingShingle |
Jenner, G. A. Dunning, G. R. Malpas, J. Brown, M. Brace, T. Bay of Islands and Little Port complexes, revisited: age, geochemical and isotopic evidence confirm suprasubduction-zone origin |
author_facet |
Jenner, G. A. Dunning, G. R. Malpas, J. Brown, M. Brace, T. |
author_sort |
Jenner, G. A. |
title |
Bay of Islands and Little Port complexes, revisited: age, geochemical and isotopic evidence confirm suprasubduction-zone origin |
title_short |
Bay of Islands and Little Port complexes, revisited: age, geochemical and isotopic evidence confirm suprasubduction-zone origin |
title_full |
Bay of Islands and Little Port complexes, revisited: age, geochemical and isotopic evidence confirm suprasubduction-zone origin |
title_fullStr |
Bay of Islands and Little Port complexes, revisited: age, geochemical and isotopic evidence confirm suprasubduction-zone origin |
title_full_unstemmed |
Bay of Islands and Little Port complexes, revisited: age, geochemical and isotopic evidence confirm suprasubduction-zone origin |
title_sort |
bay of islands and little port complexes, revisited: age, geochemical and isotopic evidence confirm suprasubduction-zone origin |
publisher |
Canadian Science Publishing |
publishDate |
1991 |
url |
http://dx.doi.org/10.1139/e91-146 http://www.nrcresearchpress.com/doi/pdf/10.1139/e91-146 |
long_lat |
ENVELOPE(-54.398,-54.398,49.667,49.667) |
geographic |
Skinner Cove |
geographic_facet |
Skinner Cove |
genre |
Newfoundland |
genre_facet |
Newfoundland |
op_source |
Canadian Journal of Earth Sciences volume 28, issue 10, page 1635-1652 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e91-146 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
28 |
container_issue |
10 |
container_start_page |
1635 |
op_container_end_page |
1652 |
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1802647058766626816 |