The Margaree orthogneiss: an Ordovician, peri-Gondwanan, mafic-felsic igneous complex in southwestern Newfoundland
The igneous protoliths of the Margaree orthogneiss intruded the peri-Gondwanan rocks of the Port-aux-Basques Complex, in the southwestern corner of the Hermitage Flexure, prior to regional deformation and metamorphism. Field relationships and UPb geochronology indicate that the Margaree orthogneiss...
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crcansciencepubl:10.1139/e00-053 2024-09-15T18:20:03+00:00 The Margaree orthogneiss: an Ordovician, peri-Gondwanan, mafic-felsic igneous complex in southwestern Newfoundland Valverde-Vaquero, Pablo Dunning, Greg R van Staal, Cees R 2000 http://dx.doi.org/10.1139/e00-053 http://www.nrcresearchpress.com/doi/pdf/10.1139/e00-053 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 37, issue 12, page 1691-1710 ISSN 0008-4077 1480-3313 journal-article 2000 crcansciencepubl https://doi.org/10.1139/e00-053 2024-08-01T04:10:03Z The igneous protoliths of the Margaree orthogneiss intruded the peri-Gondwanan rocks of the Port-aux-Basques Complex, in the southwestern corner of the Hermitage Flexure, prior to regional deformation and metamorphism. Field relationships and UPb geochronology indicate that the Margaree orthogneiss represents a 20 km long, mafic-felsic intrusive complex formed by amphibolite, dioritic orthogneiss, 474 +14 -4 Ma hornblende-bearing tonalitic orthogneiss with mafic enclaves, 472 ± 2.5 Ma and 465 ± 3 Ma biotite-bearing granitic orthogneiss, and minor ultramafic rocks. Most amphibolite have the chemistry of volcanic-arc tholeiite and are interpreted to be coeval with the intrusion of tonalitic and granitic magma with volcanic-arc geochemical signatures. Locally, mafic magmatism continued after the intrusion of the 465 Ma granite. The Margaree orthogneiss and its country rock were overprinted by upper amphibolite-facies metamorphism and deformation associated with the final closure of the Iapetus Ocean. A late-synkinematic granite dates the late stages of the high-temperature regional deformation at 417 +7 -4 Ma, while metamorphic titanite (411 ± 2 Ma) is interpreted to date extensive recrystallization under amphibolite-facies conditions as Early Devonian. The Margaree orthogneiss is broadly coeval with the plutons that postdate the Early Ordovician Penobscottian arc passive margin imbrication in central and southern Newfoundland. It also coincides with the extensive late Arenig early Llanvirn back-arc rifting event along the entire peri-Gondwanan margin of the northern Appalachians. The external position of the Port-aux-Basques Complex with respect to the back-arc elements in the Hermitage Flexure, coupled with the rock types and geochemistry of the orthogneiss, suggest formation of the Margaree orthogneiss in an arc and (or) back-arc transitional setting. Article in Journal/Newspaper Newfoundland Canadian Science Publishing Canadian Journal of Earth Sciences 37 12 1691 1710 |
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Canadian Science Publishing |
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English |
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The igneous protoliths of the Margaree orthogneiss intruded the peri-Gondwanan rocks of the Port-aux-Basques Complex, in the southwestern corner of the Hermitage Flexure, prior to regional deformation and metamorphism. Field relationships and UPb geochronology indicate that the Margaree orthogneiss represents a 20 km long, mafic-felsic intrusive complex formed by amphibolite, dioritic orthogneiss, 474 +14 -4 Ma hornblende-bearing tonalitic orthogneiss with mafic enclaves, 472 ± 2.5 Ma and 465 ± 3 Ma biotite-bearing granitic orthogneiss, and minor ultramafic rocks. Most amphibolite have the chemistry of volcanic-arc tholeiite and are interpreted to be coeval with the intrusion of tonalitic and granitic magma with volcanic-arc geochemical signatures. Locally, mafic magmatism continued after the intrusion of the 465 Ma granite. The Margaree orthogneiss and its country rock were overprinted by upper amphibolite-facies metamorphism and deformation associated with the final closure of the Iapetus Ocean. A late-synkinematic granite dates the late stages of the high-temperature regional deformation at 417 +7 -4 Ma, while metamorphic titanite (411 ± 2 Ma) is interpreted to date extensive recrystallization under amphibolite-facies conditions as Early Devonian. The Margaree orthogneiss is broadly coeval with the plutons that postdate the Early Ordovician Penobscottian arc passive margin imbrication in central and southern Newfoundland. It also coincides with the extensive late Arenig early Llanvirn back-arc rifting event along the entire peri-Gondwanan margin of the northern Appalachians. The external position of the Port-aux-Basques Complex with respect to the back-arc elements in the Hermitage Flexure, coupled with the rock types and geochemistry of the orthogneiss, suggest formation of the Margaree orthogneiss in an arc and (or) back-arc transitional setting. |
format |
Article in Journal/Newspaper |
author |
Valverde-Vaquero, Pablo Dunning, Greg R van Staal, Cees R |
spellingShingle |
Valverde-Vaquero, Pablo Dunning, Greg R van Staal, Cees R The Margaree orthogneiss: an Ordovician, peri-Gondwanan, mafic-felsic igneous complex in southwestern Newfoundland |
author_facet |
Valverde-Vaquero, Pablo Dunning, Greg R van Staal, Cees R |
author_sort |
Valverde-Vaquero, Pablo |
title |
The Margaree orthogneiss: an Ordovician, peri-Gondwanan, mafic-felsic igneous complex in southwestern Newfoundland |
title_short |
The Margaree orthogneiss: an Ordovician, peri-Gondwanan, mafic-felsic igneous complex in southwestern Newfoundland |
title_full |
The Margaree orthogneiss: an Ordovician, peri-Gondwanan, mafic-felsic igneous complex in southwestern Newfoundland |
title_fullStr |
The Margaree orthogneiss: an Ordovician, peri-Gondwanan, mafic-felsic igneous complex in southwestern Newfoundland |
title_full_unstemmed |
The Margaree orthogneiss: an Ordovician, peri-Gondwanan, mafic-felsic igneous complex in southwestern Newfoundland |
title_sort |
margaree orthogneiss: an ordovician, peri-gondwanan, mafic-felsic igneous complex in southwestern newfoundland |
publisher |
Canadian Science Publishing |
publishDate |
2000 |
url |
http://dx.doi.org/10.1139/e00-053 http://www.nrcresearchpress.com/doi/pdf/10.1139/e00-053 |
genre |
Newfoundland |
genre_facet |
Newfoundland |
op_source |
Canadian Journal of Earth Sciences volume 37, issue 12, page 1691-1710 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e00-053 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
37 |
container_issue |
12 |
container_start_page |
1691 |
op_container_end_page |
1710 |
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1810458416500441088 |