Birth of the Avalon arc in Nova Scotia, Canada: geochemical evidence for ∼700–630 Ma back-arc rift volcanism off Gondwana
Central Cape Breton Island in Nova Scotia, Canada, is host to ∼700–630 Ma felsic and associated mafic volcanic rocks that are relatively rare in other parts of the Avalon Composite Terrane, occurring elsewhere only in the Stirling Block of southern Cape Breton Island and in parts of eastern Newfound...
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Language: | English |
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Cambridge University Press (CUP)
1998
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Online Access: | http://dx.doi.org/10.1017/s0016756898008322 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756898008322 |
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crcambridgeupr:10.1017/s0016756898008322 2024-09-15T18:00:24+00:00 Birth of the Avalon arc in Nova Scotia, Canada: geochemical evidence for ∼700–630 Ma back-arc rift volcanism off Gondwana KEPPIE, J. D. DOSTAL, J. 1998 http://dx.doi.org/10.1017/s0016756898008322 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756898008322 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Geological Magazine volume 135, issue 2, page 171-181 ISSN 0016-7568 1469-5081 journal-article 1998 crcambridgeupr https://doi.org/10.1017/s0016756898008322 2024-07-31T04:04:35Z Central Cape Breton Island in Nova Scotia, Canada, is host to ∼700–630 Ma felsic and associated mafic volcanic rocks that are relatively rare in other parts of the Avalon Composite Terrane, occurring elsewhere only in the Stirling Block of southern Cape Breton Island and in parts of eastern Newfoundland. The mafic rocks of central Cape Breton Island are typically intraplate tholeiitic basalts generated by melting of a garnet-bearing mantle source. They lack a continental trace element and ε Nd imprint although they were emplaced on continental crust; they resemble oceanic island basalts. Contemporaneous volcanism in the Stirling Block is calc-alkaline and formed in a volcanic arc setting. In the absence of evidence for an intervening trench complex or suture, it may be inferred that the central Cape Breton tholeiites formed in a back-arc setting relative to the Stirling Block. This rifting may represent the initial stages of separation of an Avalonian arc from western Gondwana. The arc rifted further between ∼630–610 Ma when the younger Antigonish-Cobequid back-arc basin formed. Subsequently, the extensional arc became convergent, telescoping the back-arc basin. Northwestward migration of calc-alkaline arc magmatism may be related to shallowing of the associated Benioff zone through time. Article in Journal/Newspaper Breton Island Newfoundland Cambridge University Press Geological Magazine 135 2 171 181 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Central Cape Breton Island in Nova Scotia, Canada, is host to ∼700–630 Ma felsic and associated mafic volcanic rocks that are relatively rare in other parts of the Avalon Composite Terrane, occurring elsewhere only in the Stirling Block of southern Cape Breton Island and in parts of eastern Newfoundland. The mafic rocks of central Cape Breton Island are typically intraplate tholeiitic basalts generated by melting of a garnet-bearing mantle source. They lack a continental trace element and ε Nd imprint although they were emplaced on continental crust; they resemble oceanic island basalts. Contemporaneous volcanism in the Stirling Block is calc-alkaline and formed in a volcanic arc setting. In the absence of evidence for an intervening trench complex or suture, it may be inferred that the central Cape Breton tholeiites formed in a back-arc setting relative to the Stirling Block. This rifting may represent the initial stages of separation of an Avalonian arc from western Gondwana. The arc rifted further between ∼630–610 Ma when the younger Antigonish-Cobequid back-arc basin formed. Subsequently, the extensional arc became convergent, telescoping the back-arc basin. Northwestward migration of calc-alkaline arc magmatism may be related to shallowing of the associated Benioff zone through time. |
format |
Article in Journal/Newspaper |
author |
KEPPIE, J. D. DOSTAL, J. |
spellingShingle |
KEPPIE, J. D. DOSTAL, J. Birth of the Avalon arc in Nova Scotia, Canada: geochemical evidence for ∼700–630 Ma back-arc rift volcanism off Gondwana |
author_facet |
KEPPIE, J. D. DOSTAL, J. |
author_sort |
KEPPIE, J. D. |
title |
Birth of the Avalon arc in Nova Scotia, Canada: geochemical evidence for ∼700–630 Ma back-arc rift volcanism off Gondwana |
title_short |
Birth of the Avalon arc in Nova Scotia, Canada: geochemical evidence for ∼700–630 Ma back-arc rift volcanism off Gondwana |
title_full |
Birth of the Avalon arc in Nova Scotia, Canada: geochemical evidence for ∼700–630 Ma back-arc rift volcanism off Gondwana |
title_fullStr |
Birth of the Avalon arc in Nova Scotia, Canada: geochemical evidence for ∼700–630 Ma back-arc rift volcanism off Gondwana |
title_full_unstemmed |
Birth of the Avalon arc in Nova Scotia, Canada: geochemical evidence for ∼700–630 Ma back-arc rift volcanism off Gondwana |
title_sort |
birth of the avalon arc in nova scotia, canada: geochemical evidence for ∼700–630 ma back-arc rift volcanism off gondwana |
publisher |
Cambridge University Press (CUP) |
publishDate |
1998 |
url |
http://dx.doi.org/10.1017/s0016756898008322 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756898008322 |
genre |
Breton Island Newfoundland |
genre_facet |
Breton Island Newfoundland |
op_source |
Geological Magazine volume 135, issue 2, page 171-181 ISSN 0016-7568 1469-5081 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0016756898008322 |
container_title |
Geological Magazine |
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135 |
container_issue |
2 |
container_start_page |
171 |
op_container_end_page |
181 |
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1810437566044831744 |