Regional significance of new U–Pb age data for Neoproterozoic igneous units in Avalonian rocks of northern mainland Nova Scotia, Canada
Gondwanan Neoproterozoic tectonothermal events (Pan-African and Brasiliano) are represented in northern mainland of Nova Scotia by volcanic and sedimentary rocks assigned to the Jeffers and Georgeville groups and by gabbroic to granitoid plutons. These rocks comprise part of Avalonia, an exotic terr...
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1997
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Online Access: | http://dx.doi.org/10.1017/s0016756897006596 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756897006596 |
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crcambridgeupr:10.1017/s0016756897006596 2024-05-19T07:38:30+00:00 Regional significance of new U–Pb age data for Neoproterozoic igneous units in Avalonian rocks of northern mainland Nova Scotia, Canada MURPHY, J. BRENDAN KEPPIE, J. DUNCAN DAVIS, DON KROGH, TOM E. 1997 http://dx.doi.org/10.1017/s0016756897006596 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756897006596 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Geological Magazine volume 134, issue 1, page 113-120 ISSN 0016-7568 1469-5081 journal-article 1997 crcambridgeupr https://doi.org/10.1017/s0016756897006596 2024-04-25T06:51:40Z Gondwanan Neoproterozoic tectonothermal events (Pan-African and Brasiliano) are represented in northern mainland of Nova Scotia by volcanic and sedimentary rocks assigned to the Jeffers and Georgeville groups and by gabbroic to granitoid plutons. These rocks comprise part of Avalonia, an exotic terrane in the Appalachian orogen that was deposited in an arc-related environment along the periphery of Gondwana prior to accretion to Laurentia. Lavas sampled in the basal units of the Jeffers and Georgeville groups yielded slightly discordant U–Pb zircon and monazite data that fall on chords with upper intercept ages of 628 Ma and 617.7±1.6 Ma, respectively. Syntectonic to late syntectonic plutons intruded into these groups yielded U–Pb zircon ages of 606.6±1.6 Ma and 603 +9 −5 Ma. The former intrusion also yielded a concordant titanite age of 607±3 Ma. When combined with previously published ages, these data indicate that the back-arc deposition recorded in these groups lasted 10–15 million years (628–613 Ma) and was closely followed by c . 613–595 Ma metamorphism, intrusion and heterogeneous strike-slip related deformation. Assuming no significant shuffling of fault blocks, the relative locations of the Cobequid–Antigonish back-arc basin and the southern Cape Breton Island volcanic arc are consistent with their genesis above a north-west-dipping subduction zone. The age range of arc-related magmatism in Nova Scotia is similar to that of Avalonian rocks in southeastern Newfoundland and Britain, lending support to hypotheses of Neoproterozoic linkages. Article in Journal/Newspaper Breton Island Newfoundland Cambridge University Press Geological Magazine 134 1 113 120 |
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Cambridge University Press |
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English |
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Gondwanan Neoproterozoic tectonothermal events (Pan-African and Brasiliano) are represented in northern mainland of Nova Scotia by volcanic and sedimentary rocks assigned to the Jeffers and Georgeville groups and by gabbroic to granitoid plutons. These rocks comprise part of Avalonia, an exotic terrane in the Appalachian orogen that was deposited in an arc-related environment along the periphery of Gondwana prior to accretion to Laurentia. Lavas sampled in the basal units of the Jeffers and Georgeville groups yielded slightly discordant U–Pb zircon and monazite data that fall on chords with upper intercept ages of 628 Ma and 617.7±1.6 Ma, respectively. Syntectonic to late syntectonic plutons intruded into these groups yielded U–Pb zircon ages of 606.6±1.6 Ma and 603 +9 −5 Ma. The former intrusion also yielded a concordant titanite age of 607±3 Ma. When combined with previously published ages, these data indicate that the back-arc deposition recorded in these groups lasted 10–15 million years (628–613 Ma) and was closely followed by c . 613–595 Ma metamorphism, intrusion and heterogeneous strike-slip related deformation. Assuming no significant shuffling of fault blocks, the relative locations of the Cobequid–Antigonish back-arc basin and the southern Cape Breton Island volcanic arc are consistent with their genesis above a north-west-dipping subduction zone. The age range of arc-related magmatism in Nova Scotia is similar to that of Avalonian rocks in southeastern Newfoundland and Britain, lending support to hypotheses of Neoproterozoic linkages. |
format |
Article in Journal/Newspaper |
author |
MURPHY, J. BRENDAN KEPPIE, J. DUNCAN DAVIS, DON KROGH, TOM E. |
spellingShingle |
MURPHY, J. BRENDAN KEPPIE, J. DUNCAN DAVIS, DON KROGH, TOM E. Regional significance of new U–Pb age data for Neoproterozoic igneous units in Avalonian rocks of northern mainland Nova Scotia, Canada |
author_facet |
MURPHY, J. BRENDAN KEPPIE, J. DUNCAN DAVIS, DON KROGH, TOM E. |
author_sort |
MURPHY, J. BRENDAN |
title |
Regional significance of new U–Pb age data for Neoproterozoic igneous units in Avalonian rocks of northern mainland Nova Scotia, Canada |
title_short |
Regional significance of new U–Pb age data for Neoproterozoic igneous units in Avalonian rocks of northern mainland Nova Scotia, Canada |
title_full |
Regional significance of new U–Pb age data for Neoproterozoic igneous units in Avalonian rocks of northern mainland Nova Scotia, Canada |
title_fullStr |
Regional significance of new U–Pb age data for Neoproterozoic igneous units in Avalonian rocks of northern mainland Nova Scotia, Canada |
title_full_unstemmed |
Regional significance of new U–Pb age data for Neoproterozoic igneous units in Avalonian rocks of northern mainland Nova Scotia, Canada |
title_sort |
regional significance of new u–pb age data for neoproterozoic igneous units in avalonian rocks of northern mainland nova scotia, canada |
publisher |
Cambridge University Press (CUP) |
publishDate |
1997 |
url |
http://dx.doi.org/10.1017/s0016756897006596 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756897006596 |
genre |
Breton Island Newfoundland |
genre_facet |
Breton Island Newfoundland |
op_source |
Geological Magazine volume 134, issue 1, page 113-120 ISSN 0016-7568 1469-5081 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0016756897006596 |
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Geological Magazine |
container_volume |
134 |
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1 |
container_start_page |
113 |
op_container_end_page |
120 |
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1799477959026802688 |