40Ar/39Ar age of shear zones in the southwest Meguma Zone between Yarmouth and Meteghan, Nova Scotia

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doi: 10.1139/e17-069
Authors:Culshaw, Nicholas G.; Reynolds, Peter
Author Affiliations:Primary:
Dalhousie University, Department of Earth Sciences, Halifax, NS, Canada
Volume Title:Canadian Journal of Earth Sciences Revue Canadienne des Sciences de la Terre
Source:Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre, 34(6), p.848-853. Publisher: National Research Council of Canada, Ottawa, ON, Canada. ISSN: 0008-4077
Publication Date:1997
Note:In English with French summary. 13 refs.; illus., incl. geol. sketch map
Summary:The Cape St. Marys. Cranberry Point, and Chebogue Point shear zones lie within a zone of D2 deformation that overprinted D1 fabrics and reactivated F1 folds between the shear zones. D2 was accompanied by greenschist-facies metamorphism that variably overprinted earlier metamorphism of varying grade. A collection of single muscovite grains from pressure shadows defining L2 in a sample from the Cape St. Marys shear zone yields an average apparent age of 316±5 Ma. The age obtained for these grains from an isotope correlation diagram is 320±5 Ma. Ages for muscovite separates for two samples from the Cranberry Point shear zone are 325±4 and 319±4 Ma. An amphibolite from this zone yields a discordant spectrum interpreted to reflect the combined effects of Acadian metamorphism and excess argon. The muscovite ages approximate the time of syntectonic deformation because muscovite closure temperatures approximate the temperature of metamorphism during D2. Thus, together with published data from the Chebogue Point shear zone, our data indicate a Mid-Carboniferous age, ca. 320 Ma. for D2 within this system of three shear zones and reactivated folds.
Subjects:Absolute age; Ar/Ar; Carboniferous; Dates; Deformation; Faults; Folds; Metamorphism; Middle Carboniferous; Paleozoic; Polyphase processes; Reactivation; Shear zones; Canada; Eastern Canada; Maritime Provinces; Meguma Terrane; Nova Scotia; Yarmouth-Meteghan shear zone
Coordinates:N434500 N441500 W0660000 W0663000
Abstract Numbers:98M/53
Record ID:1997058992
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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