Three billion years of crustal evolution in eastern Canada: Constraints from receiver functions

Petrescu, L.; Bastow, I. D.; Darbyshire, F. A.; Gilligan, A.; Bodin, T.; Menke, W. et Levin, V. (2016). « Three billion years of crustal evolution in eastern Canada: Constraints from receiver functions ». Journal of Geophysical Research: Solid Earth, 121(2), pp. 788-811.

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Résumé

The geological record of SE Canada spans more than 2.5 Ga, making it a natural laboratory for the study of crustal formation and evolution over time. We estimate the crustal thickness, Poisson's ratio, a proxy for bulk crustal composition, and shear velocity (Vs) structure from receiver functions at a network of seismograph stations recently deployed across the Archean Superior Craton, the Proterozoic Grenville, and the Phanerozoic Appalachian provinces. The bulk seismic crustal properties and shear velocity structure reveal a correlation with tectonic provinces of different ages: the post-Archean crust becomes thicker, faster, more heterogeneous, and more compositionally evolved. This secular variation pattern is consistent with a growing consensus that crustal growth efficiency increased at the end of the Archean. A lack of correlation among elevation, Moho topography, and gravity anomalies within the Proterozoic belt is better explained by buoyant mantle support rather than by compositional variations driven by lower crustal metamorphic reactions. A ubiquitous ∼20 km thick high-Vs lower crustal layer is imaged beneath the Proterozoic belt. The strong discontinuity at 20 km may represent the signature of extensional collapse of an orogenic plateau, accommodated by lateral crustal flow. Wide anorthosite massifs inferred to fractionate from a mafic mantle source are abundant in Proterozoic geology and are underlain by high-Vs lower crust and a gradational Moho. Mafic underplating may have provided a source for these intrusions and could have been an important post-Archean process stimulating mafic crustal growth in a vertical sense.

Type:	Article de revue scientifique
Mots-clés ou Sujets:	Cratons, Precambrian crust, receiver functions, Canada, Bayesian inversion, H-k stacking
Unité d'appartenance:	Centres institutionnels > Centre de recherche en géochimie et géodynamique (GEOTOP) Faculté des sciences > Département des sciences de la Terre et de l'atmosphère
Déposé par:	Fiona Ann Darbyshire
Date de dépôt:	22 avr. 2016 14:52
Dernière modification:	01 oct. 2016 04:10
Adresse URL :	http://archipel.uqam.ca/id/eprint/8256

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