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Tectonic models for the origin of regional transverse structures in the Grenville Province of SW Quebec interpreted from regional gravity.

Dufréchou, Grégory; Harris, Lyal B. (2013). Tectonic models for the origin of regional transverse structures in the Grenville Province of SW Quebec interpreted from regional gravity. Journal of Geodynamics , vol. 64 . p. 15-39. DOI: 10.1016/j.jog.2012.12.001.

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Analysis of regional gravity data over the Grenville Province of SW Quebec, Canada, has identified hitherto unrecognized transverse deep-crustal structures, in addition to lineaments that correspond to mapped upper crustal, orogen-parallel tectonic boundaries. Lineaments that trend NW SE, i.e. transverse to the orogen, are interpreted as reactivated Palaeoproterozoic faults in Archaean basement that are controlled by structures in Archaean sub-crustal lithospheric mantle (SCLM). A prominent lineament (the Mont-Laurier lineament) that extends from the SE Superior Province across the SW Grenville Province is identified on both gravity and seismic tomographic imagery, the latter confirming it represents a lithospheric-scale structure. Baltica is placed at the Laurentian margin in tectonic reconstructions, and the Mont-Laurier lineament correlates with the extension towards the Superior Craton of the Belomorian Province between the Karelia and Kola cratons. It is proposed that this structure developed as a normal fault zone, and was subsequently reactivated as a transfer fault, during two orthogonal Palaeoproterozoic rifting events. The ensuing irregular basement geometry subsequently influenced sedimentation and deformation during the Grenvillian orogenic cycle and the Mont-Laurier lineament again acted as a transfer fault zone during Grenvillian orogenesis and post-orogenic collapse. Identification of tranverse structures has implications in understanding the architecture of this part of the Grenville Province. The role of pre-existing basement structures and rigid SCLM on the formation and preservation of long, linear structures transverse to an orogen throughout a complex sequence of rifting, back-arc basin formation, collisional orogenesis, and post-orogenic collapse in the Grenville Province of SW Quebec is also documented in New Guinea, with which comparisons are made.

Type de document:
Mots-clés libres: Grenville Province; bouguer gravity; seismic tomography; transverse basement faults; origin of crustal lineaments; tectonics; Baltica-Superior Craton correlations
Centre: Centre Eau Terre Environnement
Date de dépôt: 05 déc. 2016 20:47
Dernière modification: 05 déc. 2016 20:47
URI: http://espace.inrs.ca/id/eprint/3428

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