Localized Backarc Extension in an Overall Compressional Setting During the Assembly of Nuna: Geochemical and Isotopic Evidence From Orosirian (1883–1848 Ma) Mafic Magmatism of the Aillik Group, Labrador, Canada
Abstract Bimodal volcanism occurs in a range of extensional environments that are characterized by distinctive but overlapping, lithogeochemical and isotopic signatures and lithological assemblages. Where basaltic magmatism is associated with ferroan (A‐type) rhyolites, it is typically the lithogeoc...
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American Geophysical Union (AGU)
2021
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Online Access: | https://doi.org/10.1029/2020EA001489 https://doaj.org/article/88529609143842ad88a77263392fbb15 |
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ftdoajarticles:oai:doaj.org/article:88529609143842ad88a77263392fbb15 2023-05-15T17:10:03+02:00 Localized Backarc Extension in an Overall Compressional Setting During the Assembly of Nuna: Geochemical and Isotopic Evidence From Orosirian (1883–1848 Ma) Mafic Magmatism of the Aillik Group, Labrador, Canada A. M. Hinchey 2021-06-01T00:00:00Z https://doi.org/10.1029/2020EA001489 https://doaj.org/article/88529609143842ad88a77263392fbb15 EN eng American Geophysical Union (AGU) https://doi.org/10.1029/2020EA001489 https://doaj.org/toc/2333-5084 2333-5084 doi:10.1029/2020EA001489 https://doaj.org/article/88529609143842ad88a77263392fbb15 Earth and Space Science, Vol 8, Iss 6, Pp n/a-n/a (2021) Nd isotopic data supercontinent assembly major and trace element geochemistry paleoproterozoic orogens backarc basin mafic volcanism Astronomy QB1-991 Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.1029/2020EA001489 2022-12-31T05:33:15Z Abstract Bimodal volcanism occurs in a range of extensional environments that are characterized by distinctive but overlapping, lithogeochemical and isotopic signatures and lithological assemblages. Where basaltic magmatism is associated with ferroan (A‐type) rhyolites, it is typically the lithogeochemistry and isotopic systematics of the basaltic rocks that are the most beneficial in constraining the tectonic evolution. This study presents geochemical and isotopic data from mafic volcanic rocks of the bimodal Aillik Group, that formed during the assembly of the Paleoproterozoic supercontinent Nuna. Lithogeochemical signatures define two suites. Suite 1 samples have N‐MORB (Normal‐Mid‐Ocean Ridge Basalt) chemical affinities such as flat HREE, and smooth but flat LREE and have εNd(t = 1860 Ma) values between +2.8 and +4.8. Suite 2 samples typically have compositions between N‐MORB and IAT (Island Arc Tholeiites) basalts, with variable REE patterns ranging from IAT to OIB (Ocean Island Basalt). The basalts display moderately developed subduction zone signatures, such as negative Nb and Ti, and have εNd(t = 1860 Ma) ranging from −3.4 to +2.2. Geochemical variability within the Aillik Group mafic rocks is explained by processes active in arc settings and involves mixing between depleted mantle components with variable contributions from crustal and subducted‐slab sources. Coupled with field evidence, the geochemical and isotopic data support emplacement of the basalt in an extensional, backarc basin setting. This backarc basin formed due to localized extension during Nuna assembly. The Makkovik Province preserves a complex orogen characterized by multiple diachronous, compressional, and extensional events along a long‐lived active margin of the Archean North Atlantic Craton. Article in Journal/Newspaper Makkovik North Atlantic Ocean Island Directory of Open Access Journals: DOAJ Articles Canada Makkovik ENVELOPE(-59.178,-59.178,55.087,55.087) Earth and Space Science 8 6 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Nd isotopic data supercontinent assembly major and trace element geochemistry paleoproterozoic orogens backarc basin mafic volcanism Astronomy QB1-991 Geology QE1-996.5 |
spellingShingle |
Nd isotopic data supercontinent assembly major and trace element geochemistry paleoproterozoic orogens backarc basin mafic volcanism Astronomy QB1-991 Geology QE1-996.5 A. M. Hinchey Localized Backarc Extension in an Overall Compressional Setting During the Assembly of Nuna: Geochemical and Isotopic Evidence From Orosirian (1883–1848 Ma) Mafic Magmatism of the Aillik Group, Labrador, Canada |
topic_facet |
Nd isotopic data supercontinent assembly major and trace element geochemistry paleoproterozoic orogens backarc basin mafic volcanism Astronomy QB1-991 Geology QE1-996.5 |
description |
Abstract Bimodal volcanism occurs in a range of extensional environments that are characterized by distinctive but overlapping, lithogeochemical and isotopic signatures and lithological assemblages. Where basaltic magmatism is associated with ferroan (A‐type) rhyolites, it is typically the lithogeochemistry and isotopic systematics of the basaltic rocks that are the most beneficial in constraining the tectonic evolution. This study presents geochemical and isotopic data from mafic volcanic rocks of the bimodal Aillik Group, that formed during the assembly of the Paleoproterozoic supercontinent Nuna. Lithogeochemical signatures define two suites. Suite 1 samples have N‐MORB (Normal‐Mid‐Ocean Ridge Basalt) chemical affinities such as flat HREE, and smooth but flat LREE and have εNd(t = 1860 Ma) values between +2.8 and +4.8. Suite 2 samples typically have compositions between N‐MORB and IAT (Island Arc Tholeiites) basalts, with variable REE patterns ranging from IAT to OIB (Ocean Island Basalt). The basalts display moderately developed subduction zone signatures, such as negative Nb and Ti, and have εNd(t = 1860 Ma) ranging from −3.4 to +2.2. Geochemical variability within the Aillik Group mafic rocks is explained by processes active in arc settings and involves mixing between depleted mantle components with variable contributions from crustal and subducted‐slab sources. Coupled with field evidence, the geochemical and isotopic data support emplacement of the basalt in an extensional, backarc basin setting. This backarc basin formed due to localized extension during Nuna assembly. The Makkovik Province preserves a complex orogen characterized by multiple diachronous, compressional, and extensional events along a long‐lived active margin of the Archean North Atlantic Craton. |
format |
Article in Journal/Newspaper |
author |
A. M. Hinchey |
author_facet |
A. M. Hinchey |
author_sort |
A. M. Hinchey |
title |
Localized Backarc Extension in an Overall Compressional Setting During the Assembly of Nuna: Geochemical and Isotopic Evidence From Orosirian (1883–1848 Ma) Mafic Magmatism of the Aillik Group, Labrador, Canada |
title_short |
Localized Backarc Extension in an Overall Compressional Setting During the Assembly of Nuna: Geochemical and Isotopic Evidence From Orosirian (1883–1848 Ma) Mafic Magmatism of the Aillik Group, Labrador, Canada |
title_full |
Localized Backarc Extension in an Overall Compressional Setting During the Assembly of Nuna: Geochemical and Isotopic Evidence From Orosirian (1883–1848 Ma) Mafic Magmatism of the Aillik Group, Labrador, Canada |
title_fullStr |
Localized Backarc Extension in an Overall Compressional Setting During the Assembly of Nuna: Geochemical and Isotopic Evidence From Orosirian (1883–1848 Ma) Mafic Magmatism of the Aillik Group, Labrador, Canada |
title_full_unstemmed |
Localized Backarc Extension in an Overall Compressional Setting During the Assembly of Nuna: Geochemical and Isotopic Evidence From Orosirian (1883–1848 Ma) Mafic Magmatism of the Aillik Group, Labrador, Canada |
title_sort |
localized backarc extension in an overall compressional setting during the assembly of nuna: geochemical and isotopic evidence from orosirian (1883–1848 ma) mafic magmatism of the aillik group, labrador, canada |
publisher |
American Geophysical Union (AGU) |
publishDate |
2021 |
url |
https://doi.org/10.1029/2020EA001489 https://doaj.org/article/88529609143842ad88a77263392fbb15 |
long_lat |
ENVELOPE(-59.178,-59.178,55.087,55.087) |
geographic |
Canada Makkovik |
geographic_facet |
Canada Makkovik |
genre |
Makkovik North Atlantic Ocean Island |
genre_facet |
Makkovik North Atlantic Ocean Island |
op_source |
Earth and Space Science, Vol 8, Iss 6, Pp n/a-n/a (2021) |
op_relation |
https://doi.org/10.1029/2020EA001489 https://doaj.org/toc/2333-5084 2333-5084 doi:10.1029/2020EA001489 https://doaj.org/article/88529609143842ad88a77263392fbb15 |
op_doi |
https://doi.org/10.1029/2020EA001489 |
container_title |
Earth and Space Science |
container_volume |
8 |
container_issue |
6 |
_version_ |
1766066459750957056 |