Les contraintes phanérozoïques dans la plate-forme du Saint-Laurent, région de Montréal, Québec

The tectonic evolution of the Appalachian platform is still not well understood. The Montréal area, however, shows evidence of major fracturing events, some of which cut the Cretaceous intrusions. The history of the different stress events recorded in the platform was studied by the analysis of brittle faults and dykes, followed by the calculation, by way inversion of tensors, of the corresponding stresses. The tectonics represented is polyphased and its analysis allows a historical reconstitution of the carbonate and flyschoid platform since the Lower Paleozoic. Five tectonic stages are recognized, corresponding to the major geodynamic events characteristics of northeast North America: (i) early north–south distensional events; (ii) Appalachian compression in a west-northwest–east-southeast direction; (iii) terminal Appalachian compression oriented north-northeast–south-southwest; (iv) Cretaceous north–south distension; (v) a Cenozoic to Recent compression in a northwest–southeast direction. [Journal Translation]