The Bras d’Or terrane of central Cape Breton Island, Nova Scotia, Canada, contains a well-preserved record of the Ediacaran to early Cambrian evolution of Ganderia, a Gondwana-derived terrane in the northern Appalachian orogen. A complex assemblage of low- to high-grade metasedimentary rocks has varied detrital zircon signatures from laser ablation inductively coupled plasma mass spectrometry U-Pb zircon dating, but combining three or more samples yielded representative age spectra that support correlation of the low- and high-grade metasedimentary rocks throughout the Bras d’Or terrane and the corresponding Ganderian Brookville terrane of southern New Brunswick. In quartzite samples from the McMillan Flowage Formation in the northwestern Bras d’Or terrane, the youngest detrital zircons have ages >900 Ma, in contrast to previously studied psammitic and semipelitic samples from correlative units in the eastern Bras d’Or terrane in which youngest detrital ages are 620–600 Ma. Both quartzite and semipelitic samples from the McMillan Flowage Formation contain Neoproterozoic dates from zircon rims, which reflect metamorphic overgrowths during peak metamorphism at ca. 550 Ma, providing a robust age for peak metamorphism in the Bras d’Or terrane that supports similar, albeit sparse, ages reported previously from monazite and titanite samples. This metamorphism is coeval with the emplacement of voluminous dioritic to granitic plutons that occur throughout the Bras d’Or terrane and form in an Andean-type continental margin subduction zone. New U-Pb zircon ages presented here from plutons in the northern Bras d’Or terrane, combined with previously published ages, are consistent with subduction-related magmatism and associated metamorphism between ca. 575 and 540 Ma.
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January 10, 2023
U-Pb zircon ages from metasedimentary and plutonic rocks in the Bras d’Or terrane of Cape Breton Island, Nova Scotia, Canada: insights into the Ediacaran–Cambrian tectonomagmatic evolution of Ganderia
Deanne van Rooyen;
(Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing)
a
Department of Earth and Environmental Science, Acadia University, Wolfville, NS B4P 2R6, CanadaCorresponding author: Deanne van Rooyen (email: [email protected])
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Sandra M. Barr;
Sandra M. Barr
(Conceptualization, Formal analysis, Funding acquisition, Investigation, Resources, Writing – original draft, Writing – review & editing)
a
Department of Earth and Environmental Science, Acadia University, Wolfville, NS B4P 2R6, Canada
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Chris E. White;
Chris E. White
(Conceptualization, Data curation, Formal analysis, Investigation, Writing – review & editing)
b
Geoscience and Mines Branch, Nova Scotia Department of Energy and Mines, Halifax, NS B3J 2T9, Canada
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James L. Crowley
James L. Crowley
(Data curation, Formal analysis, Methodology, Software, Validation)
c
Department of Geoscience, Boise State University, Boise, ID 83725, USA
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Deanne van Rooyen
Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing
a
Department of Earth and Environmental Science, Acadia University, Wolfville, NS B4P 2R6, Canada
Sandra M. Barr
Conceptualization, Formal analysis, Funding acquisition, Investigation, Resources, Writing – original draft, Writing – review & editing
a
Department of Earth and Environmental Science, Acadia University, Wolfville, NS B4P 2R6, Canada
Chris E. White
Conceptualization, Data curation, Formal analysis, Investigation, Writing – review & editing
b
Geoscience and Mines Branch, Nova Scotia Department of Energy and Mines, Halifax, NS B3J 2T9, Canada
James L. Crowley
Data curation, Formal analysis, Methodology, Software, Validation
c
Department of Geoscience, Boise State University, Boise, ID 83725, USACorresponding author: Deanne van Rooyen (email: [email protected])
Publisher: Canadian Science Publishing
Received:
19 Sep 2022
Accepted:
25 Nov 2022
Accepted Manuscript:
10 Jan 2023
First Online:
09 May 2023
Online ISSN: 1480-3313
Print ISSN: 0008-4077
The Author(s)
Permission for reuse (free in most cases) can be obtained from copyright.com.
Canadian Journal of Earth Sciences (2023) 60 (5): 485–512.
Article history
Received:
19 Sep 2022
Accepted:
25 Nov 2022
Accepted Manuscript:
10 Jan 2023
First Online:
09 May 2023
Citation
Deanne van Rooyen, Sandra M. Barr, Chris E. White, James L. Crowley; U-Pb zircon ages from metasedimentary and plutonic rocks in the Bras d’Or terrane of Cape Breton Island, Nova Scotia, Canada: insights into the Ediacaran–Cambrian tectonomagmatic evolution of Ganderia. Canadian Journal of Earth Sciences 2023;; 60 (5): 485–512. doi: https://doi.org/10.1139/cjes-2022-0103
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Index Terms/Descriptors
- absolute age
- Cambrian
- Canada
- Cape Breton Island
- Eastern Canada
- IGCP
- igneous rocks
- intrusions
- lithostratigraphy
- Maritime Provinces
- metamorphic rocks
- metasedimentary rocks
- Neoproterozoic
- nesosilicates
- Nova Scotia
- orthosilicates
- Paleozoic
- plutonic rocks
- plutons
- Precambrian
- Proterozoic
- quartzites
- schists
- silicates
- U/Pb
- upper Precambrian
- zircon
- zircon group
- Bras d'Or Terrane
- McMillan Flowage Formation
- Morrison Brook Pluton
- Cross Mountain Pluton
- Murray Brook Pluton
- Broad Cove Pluton
- Highlands North Pluton
- Highlands Pluton
Latitude & Longitude
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