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TitleCrustal development at the pre-Grenvillian Laurentian margin: a record from contrasting geochemistry of mafic and ultramafic orthogneisses in the Chochocouane River area, Quebec
AuthorLa Flèche, M R; Birkett, T C; Corriveau, LORCID logo
SourceThe Grenville Province: a geological and mineral resources perspective derived from government and academic research initiatives/La Province de Grenville : l'aspect des ressources géologiques et minérales découlant des initiatives de recherche gouvernementales et académiques; Canadian Journal of Earth Sciences vol. 42, no. 10, 2005 p. 1653-1675,
Alt SeriesEarth Sciences Sector, Contribution Series 2005192
PublisherCanadian Science Publishing
Mediapaper; on-line; digital
File formatpdf (Adobe Acrobat Reader)
NTS31N/15; 31N/16; 31O/13; 31O/14; 32B/03; 32B/04; 32B/05; 32C/01; 32B/02; 32B/08
AreaChochocouane River
Lat/Long WENS-77.0000 -48.5000 75.5000 47.5000
Subjectsgeochemistry; igneous and metamorphic petrology; Archean; crustal evolution; tectonic history; plate margins; mafic rocks; ultramafic rocks; metasedimentary rocks; orthogneisses; paragneisses; gneisses; metavolcanic rocks; komatiites; andesites; igneous rocks; autochthons; allochthons; geochemical analyses; trace element analyses; major element analyses; isotope ratios; neodymium samarium dates; petrogenesis; oceanic crust; tholeiites; continental crust; amphibolites; magmatism; magmas; subduction; downgoing slab; intrusions; metamorphism; metasomatism; granulite facies; emplacement; relative ages; greenstone belts; rifting; source rocks; x-ray fluorescence analyses; rock analyses, rare earth elements; tonalites; monzonites; plate boundaries; terranes; tectonic setting; petrography; Grenville Province; Grenville Front; Superior Province; Laurentia; Laurentian Margin; Chochocouane complex; Temiscamingue terrane; Attic tonalitic complex; Pascagama tonalitic complex; Serpent comlex; Kenoran Orogeny; Abitibi Subprovince; Circum-Superior Belt; Precambrian; Proterozoic
Illustrationssketch maps; tables; geochemical plots; ternary diagrams; histograms; isochron diagrams; pseudo-ternary projections
ProgramConsolidating Canada's Geoscience Knowledge
ProgramMinistère des Ressources naturelles et de la Faune du Québec, Programme de financement
Released2005 10 01
AbstractMafic and ultramafic orthogneisses from the western Grenville Province of Quebec adjacent to the Archean Superior Province (Canada) display geochemical characteristics that highlight processes that shaped the pre-Grenvillian Laurentian margin through late Archean to Mesoproterozoic time. Group I mafic and ultramafic granulites of the Parautochthonous Belt compositions overlap Archean Abitibi metavolcanic rocks (komatiites to Fe-rich andesites) supporting their autochthonous character. Limited variation of incompatible trace-element ratios with increasing differentiation suggests minimal sialic crust assimilation during petrogenesis and probable formation in an oceanic setting. Group II mafic tholeiites occur within both the Parautochthonous Belt and the Allochthonous Polycyclic Belt. Their compositions differ significantly from those of Archean rocks but overlap those of Proterozoic and modern continental tholeiites. Group III mafic calc-alkaline amphibolites, predominantly in the Allochthonous Polycyclic Belt, display chemical characteristics expected of magma derivation from subducted oceanic crust. In contrast to group I Archean meta-igneous rocks metamorphosed during the Kenoran orogeny, group III rocks do not record an early phase of large-ion lithophile element (LILE) metasomatism and granulite-facies metamorphism. As such, their emplacement is interpreted to postdate the Archean Kenoran metamorphism and to be Proterozoic in age. Group I rocks reflect an Archaean ensimatic greenstone belt environment; group II tholeiites reflect a Proterozoic continental rift environment; and group III rocks reflect a subduction-related source, possibly related to Andean-style, calc-alkaline magmatism.

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