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Detrital chromites reveal Slave Craton's missing komatiite

Rasmus Haugaard, Pedro Waterton, Luke Ootes, D. Graham Pearson, Yan Luo and Kurt Konhauser
Detrital chromites reveal Slave Craton's missing komatiite
Geology (Boulder) (May 2021) 49 (9): 1079-1083


Komatiitic magmatism is a characteristic feature of Archean cratons, diagnostic of the addition of juvenile crust, and a clue to the thermal evolution of early Earth lithosphere. The Slave craton in northwest Canada contains >20 greenstone belts but no identified komatiite. The reason for this dearth of komatiite, when compared to other Archean cratons, remains enigmatic. The Central Slave Cover Group (ca. 2.85 Ga) includes fuchsitic quartzite with relict detrital chromite grains in heavy-mineral laminations. Major and platinum group element systematics indicate that the chromites were derived from Al-undepleted komatiitic dunites. The chromites have low (super 187) Os/ (super 188) Os ratios relative to chondrite with a narrow range of rhenium depletion ages at 3.19 + or - 0.12 Ga. While these ages overlap a documented crust formation event, they identify an unrecognized addition of juvenile crust that is not preserved in the bedrock exposures or the zircon isotopic data. The documentation of komatiitic magmatism via detrital chromites indicates a region of thin lithospheric mantle at ca. 3.2 Ga, either within or at the edge of the protocratonic nucleus. This study demonstrates the applicability of detrital chromites in provenance studies, augmenting the record supplied by detrital zircons.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 49
Serial Issue: 9
Title: Detrital chromites reveal Slave Craton's missing komatiite
Affiliation: Laurentian University, Harquail School of Earth Sciences, Sudbury, ON, Canada
Pages: 1079-1083
Published: 20210519
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 35
Accession Number: 2021-070635
Categories: Igneous and metamorphic petrologyGeochemistry of rocks, soils, and sediments
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. col., geol. sketch map
N62°30'00" - N63°00'00", W115°00'00" - W114°00'00"
Secondary Affiliation: University of Alberta, Edmonton, AB, CAN, CanadaBritish Columbia Geological Survey, Victoria, BC, CAN, Canada
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 202149
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