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TitleGeochemistry and petrogenesis of the Lapeyrère gabbronorite, south-central Grenville Province, Quebec
DownloadDownload (whole publication)
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorNadeau, L; Brouillette, P; Bédard, J
SourceCanadian Shield/Bouclier canadien; by Geological Survey of Canada; Geological Survey of Canada, Current Research no. 1998-C, 1998 p. 179-188, Open Access logo Open Access
PublisherNatural Resources Canada
Mediapaper; on-line; digital
RelatedThis publication is contained in Geological Survey of Canada; (1998). Canadian shield, Geological Survey of Canada, Current Research no. 1998-C
File formatpdf
NTS31P/01SW; 31P/01NW; 31P/08SW; 31P/08NW
Lat/Long WENS-72.5000 -72.2500 47.4000 47.1333
Subjectsgeochemistry; igneous and metamorphic petrology; lithology; gabbros; igneous rocks; petrographic analyses; major element analyses; trace element analyses; analyses; geochemical analyses; tectonic interpretations; Lapeyrère gabbronorite; Proterozoic
Illustrationssketch maps; analyses
Released1998 03 01
AbstractThe Lapeyrère gabbronorite is the largest of a number of post-collisional, mid-crustal gabbroic intrusions in Grenvillian terrain of the Portneuf-Mauricie region. These intrusions contain no significant amount of anorthosite and are 60-70 Ma younger than the much larger neighbouring Morin and Lac Saint-Jean anorthosite-mangerite-charnockite-granite complexes.
Whole-rock geochemistry shows unidirectional trends and large overlaps from þhornblende-free' gabbronorite to þpyroxene-free' hornblende-quartz-diorite and granodiorite, consistent with diversification from the same parent magma.
The flat distribution in heavy rare-earth elements and the low Ti/Y ratios of model liquids in equilibrium with the cumulate phases suggest extraction of gabbronorite parent magma from a shallow-mantle spinel-lherzolite reservoir, which contrasts with the deeper mantle-plume-related setting commonly invoked for anorthosite-mangerite-charnockite-granite magmatism. Partial melting in upper mantle reservoirs is consistent with intrusion of the Lapeyrère gabbronorite at the initial stage of orogenic collapse, following convective thinning of the lithospheric mantle.

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