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Variation in plagioclase clouding intensity in Matachewan dykes; evidence for the exhumation history of the northern margin of the Sudbury igneous complex

J. P. Siddorn and H. C. Halls
Variation in plagioclase clouding intensity in Matachewan dykes; evidence for the exhumation history of the northern margin of the Sudbury igneous complex
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (June 2002) 39 (6): 933-942

Abstract

Early Proterozoic Matachewan mafic dykes that cut the Archean Cartier granite-Levack Gneiss Complex north of the Sudbury Igneous Complex (SIC), Canada, are generally metamorphosed to lower amphibolite facies but exhibit locally unaltered plagioclase. These plagioclase feldspars display a clouding similar to that found in the same swarm in the vicinity of the Kapuskasing uplift, about 200 km to the northwest, where the clouding intensity is due to magnetite exsolution and displays a positive correlation with the depth of dyke emplacement. In the Sudbury area, the clouding intensity, obtained by image analysis of thin sections, increases away from the SIC, opposite to the direction of increasing regional metamorphism in the Archean basement. This suggests that the Levack Gneiss Complex north of the SIC was exhumed prior to the intrusion of 2.47 Ga Matachewan dykes and therefore predates the formation of the SIC and associated impact event. The southward tilting of the crust inferred from the plagioclase-clouding data appears to have involved uplift along the Benny Deformation Zone, but the exact age of this deformation is unknown. It may be associated with the 1.8-1.9 Penokean Orogen, 1.85 Ga Sudbury impact crater, or 2.2-2.4 Ga Blezardian Orogen.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 39
Serial Issue: 6
Title: Variation in plagioclase clouding intensity in Matachewan dykes; evidence for the exhumation history of the northern margin of the Sudbury igneous complex
Affiliation: University of Toronto, Department of Geology, Toronto, ON, Canada
Pages: 933-942
Published: 200206
Text Language: English
Summary Language: French
Publisher: National Research Council of Canada, Ottawa, ON, Canada
References: 49
Accession Number: 2002-067090
Categories: Igneous and metamorphic petrologyStructural geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendix
Illustration Description: illus. incl. geol. sketch maps
N46°49'60" - N46°49'60", W81°00'00" - W81°00'00"
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200221
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