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Geochemistry, geochronology, and radiogenic isotopes of the Balmer and Confederation Assemblages of the Laird Lake area, Red Lake greenstone belt, Canada; implications for Archean tectonic evolution

Brigitte R. Gelinas, Pete Hollings and Richard Friedman
Geochemistry, geochronology, and radiogenic isotopes of the Balmer and Confederation Assemblages of the Laird Lake area, Red Lake greenstone belt, Canada; implications for Archean tectonic evolution
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (June 2024) 61 (6): 686-711

Abstract

The Laird Lake property, southwest Red Lake greenstone belt, straddles the contact between the Balmer (2.99-2.96 Ga) and the Confederation (2.74-2.73 Ga) assemblages. The property is 10 km along strike from the Madsen and Starrat-Olsen Au mines that are hosted near the contact. The Balmer assemblage consists of fine-grained, aphyric, locally pillowed mafic volcanic rocks, ultramafic intrusive and volcanic rocks with flow breccia textures hosting local spinifex-bearing clasts, and banded-iron formations. In contrast, the Confederation assemblage comprises porphyritic mafic volcanic rocks intercalated with intermediate to felsic volcanic rocks that include crystal lapilli tuffs, crystal tuffs, and tuffs. The Balmer assemblage is composed of tholeiitic mafic volcanic rocks with minor Al-undepleted komatiites, whereas the Confederation assemblage is calc-alkalic. Neodymium isotopes, in conjunction with trace element geochemistry, suggests that parts of the Balmer assemblage were weakly contaminated by an older intermediate basement. Both arc and back-arc volcanism occurs in the Confederation assemblage, with the arc rocks showing a stronger crustal component than the back-arc rocks. A maximum U-Pb age of 2741 + or - 19 Ma for a crystal tuff and an age of 2737.68 + or - 0.79 Ma for a diorite are consistent with a Confederation assemblage affinity for the intermediate calc-alkaline rocks south of the Au-bearing horizon. The Balmer assemblage represents an oceanic plateau formed by plume magmatism on the margins of the North Caribou Terrane, whereas the Confederation assemblage at Laird Lake formed in an oceanic arc setting where both arc and back-arc volcanism occurred simultaneously.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 61
Serial Issue: 6
Title: Geochemistry, geochronology, and radiogenic isotopes of the Balmer and Confederation Assemblages of the Laird Lake area, Red Lake greenstone belt, Canada; implications for Archean tectonic evolution
Affiliation: Lakehead University, Department of Geology, Thunder Bay, ON, Canada
Pages: 686-711
Published: 202406
Text Language: English
Publisher: National Research Council of Canada, Ottawa, ON, Canada
References: 92
Accession Number: 2024-048565
Categories: Igneous and metamorphic petrologyIsotope geochemistryGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, geol. sketch maps
N50°55'60" - N50°55'60", W94°05'60" - W94°05'60"
Secondary Affiliation: University of British Columbia, CAN, Canada
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2024, American Geosciences Institute. Reference includes data from Canadian Science Publishing, NRC Research Press, Ottawa, ON, Canada. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202429

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