The Hudson Bay Lithospheric Experiment (HuBLE): insights into Precambrian plate tectonics and the development of mantle keels

Bastow, I. D.; Eaton, D. W.; Kendall, J.- M.; Helffrich, G.; Snyder, D. B.; Thompson, D. A.; Wookey, J.; Darbyshire, F. A. et Pawlak, A. E. (2015). « The Hudson Bay Lithospheric Experiment (HuBLE): insights into Precambrian plate tectonics and the development of mantle keels ». Geological Society, London, Special Publications, 389(1), pp. 41-67.

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Résumé

Hudson Bay Lithospheric Experiment (HuBLE) was designed to understand the processes that formed Laurentia and the Hudson Bay basin within it. Receiver function analysis shows that Archaean terranes display structurally simple, uniform thickness, felsic crust. Beneath the Palaeoproterozoic Trans-Hudson Orogen (THO), thicker, more complex crust is interpreted as evidence for a secular evolution in crustal formation from non-plate-tectonic in the Palaeoarchaean to fully developed plate tectonics by the Palaeoproterozoic. Corroborating this hypothesis, anisotropy studies reveal 1.8 Ga plate-scale THO-age fabrics. Seismic tomography shows that the Proterozoic mantle has lower wavespeeds than surrounding Archaean blocks; the Laurentian keel thus formed partly in post-Archaean times. A mantle transition zone study indicates ‘normal’ temperatures beneath the Laurentian keel, so any cold mantle down-welling associated with the regional free-air gravity anomaly is probably confined to the upper mantle. Focal mechanisms from earthquakes indicate that present-day crustal stresses are influenced by glacial rebound and pre-existing faults. Ambient-noise tomography reveals a low-velocity anomaly, coincident with a previously inferred zone of crustal stretching, eliminating eclogitization of lower crustal rocks as a basin formation mechanism. Hudson Bay is an ephemeral feature, caused principally by incomplete glacial rebound. Plate stretching is the primary mechanism responsible for the formation of the basin itself.

Type:	Article de revue scientifique
Informations complémentaires:	Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.
Mots-clés ou Sujets:	Basin evolution, formation mechanism, Laurentia, mantle, plate tectonics, Precambrian, seismic tomography, transition zone
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 14:55
Dernière modification:	25 avr. 2016 15:49
Adresse URL :	http://archipel.uqam.ca/id/eprint/8262

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