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TitreCumberland batholith, Trans-Hudson Orogen, Canada: Petrogenesis and implications for Paleoproterozoic crustal and orogenic processes
AuteurWhalen, J B; Wodicka, N; Taylor, B E; Jackson, G D
SourceLithos vol. 117, no. 1-4, 2010 p. 99-118, https://doi.org/10.1016/j.lithos.2010.02.008
Année2010
Séries alt.Secteur des sciences de la Terre, Contribution externe 20090332
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1016/j.lithos.2010.02.008
Mediapapier; en ligne; numérique
Formatspdf
ProvinceNunavut
SNRC25; 26; 27A; 27B; 27C; 36; 37A
Lat/Long OENS-80.0000 -60.0000 72.0000 61.0000
Sujetspétrogenèse; orogenèse; régions orogéniques; roches ignées; roches plutoniques; batholites; milieux tectoniques; interprétations tectoniques; cadre tectonique; géochimie des éléments en trace; géochimie des éléments majeurs; magmatisme; Batholite de Cumberland ; Orogène de Trans-hudson ; tectonique; géochronologie; géochimie; Précambrien; Protérozoïque
Illustrationslocation maps; tables; plots; histograms; ternary diagrams
ProgrammeGEM : La géocartographie de l'énergie et des minéraux - la composante GEM minéraux, GEM : La géocartographie de l'énergie et des minéraux
Résumé(disponible en anglais seulement)
Large volume, plutonic belts, such as the ~221,000 km2, ca. 1.865 - 1.845 Ga Cumberland batholith (CB) of the Trans-Hudson Orogen in Canada, are major components of Paleoproterozoic orogenic belts. In many cases, they have been interpreted as continental arc batholiths. The petrogenesis and tectonic context of the CB and implications for crustal growth and recycling are interpreted herein based on a 900 km geochemical-isotopic (Nd - O) transect across it and into granitoid plutons within bounding Archean cratons in central and southern Baffin Island.
The mainly granulite grade CB, emplaced over an age span of between 14 and 24 Ma, consists mainly of high-K to shoshonitic monzogranite and granodiorite, but also includes low- and medium-K granitoid rocks. Metaluminous to slightly peraluminous compositions and delta18O (VSMOW) values (+ 6 to + 10permil) indicate derivation from infracrustal (I-type) sources. EpsilonNd 1.85 Ga signatures (-12 to -2) of both mafic and felsic units suggest a dominance of evolved sources. Isotopic signatures in the interior of the CB (-2 to -7) are more radiogenic than those within Archean domains in central (-8 to -15) and southern (-5 to -19) Baffin Island. The isotopic transect is interpreted as 'imaging' an accreted microcontinental block (Meta Incognita) and bounding Archean cratons. The CB includes granites of arc, within-plate (A-type) and post-collisional affinity and volumetrically minor mafic rocks with both arc and non-arc features. (La/Yb)CN and Sr/Y values range from < 1 to 225 and < 1 to 611, respectively. In these respects, some CB granitoid rocks resemble Paleozoic adakitic granites, interpreted as partial melts of greatly thickened crust within post-collisional settings, such as Tibet. Thus, the CB likely encompasses various non-consanguineous magmatic suites generated at deep- to mid-crustal depths. Although CB granitoid rocks undoubtedly had important crustal sources, it is hard to assess the relative contribution of mantle-derived magmas.
The CB is best interpreted as a post-accretion batholith resulting from large-scale lithospheric mantle delamination followed by the upwelling of hot asthenospheric mantle leading to voluminous crustal partial melting. Contributors to crustal instability which may have facilitated such delamination included: (a) a collage of recently assembled small cratons underlain by hot, weak lithosphere with mantle-depth structural breaks within this segment of the Trans-Hudson Orogen; (b) the gabbro-eclogite phase transformation, and (c) a greatly thickened crustal section (> 60 km), as evidenced by adakitic granites.
GEOSCAN ID261478