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

Gélard, Jean-Pierre; Jébrak, Michel; Prichonnet, Gilbert

doi:10.1139/e92-043

Cited by 6 publications

(5 citation statements)

References 19 publications

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“…3), where a N166°/70°sinistral fault that is mechanically compatible with this stress orientation is crosscut by a Cretaceous sill (Faure et al 1996). In the Montréal area, the ESE-WNW compression observed at four sites indicates that regional NW-SE-and east-west-trending strikeslip faults developed before Mesozoic time, as previously suggested before by Gélard et al (1992), likely during the late Ordovician. Similar fault geometry and stress tensor axes have been recognized by Rocher and Tremblay (2001) and Rocher et al (2003) near Québec City and Montréal areas, respectively.…”

Section: Taconian Stress In the Humber Zone And St Lawrence Lowlandssupporting

confidence: 66%

“…Their findings have been essential to understanding the dynamics of deformational processes and the direction of the tectonic transport. On the other hand, there are relatively few studies in the northern Appalachians that focus on brittle features (faults, veins, joints) and their significance in terms of paleostress analysis (Faure et al 1992;Gélard et al 1992;Malo and Bourque 1993;Trudel and Malo 1993;Rocher et al 2003). Slip-faults yield quantitative information about the geometry of paleostress tensors and the directions of compressional and (or) extensional stress axes.…”

Section: Introductionmentioning

confidence: 99%

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Reconstruction of Taconian and Acadian paleostress regimes in the Quebec and northern New Brunswick Appalachians

Faure¹,

Tremblay²,

Malo³

2004

Can. J. Earth Sci.

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A numerical analysis of fault populations was applied in the Quebec and northern New Brunswick Appalachians to characterize paleostress fields attributed to the Taconian and Acadian orogenies. The first brittle deformation documented in the external domain of the Humber Zone is associated with the thin-skinned tectonics of the Taconian orogen. The Taconian brittle deformation, characterized by north-south to NE-SW reverse conjugated brittle faults, evolved under a pure shear compressional regime (vertical σ3 axes) with σ1 axes oriented ESE-WNW. The ENE-WSW dextral and NW-SE sinistral faults that are observed in the St.Lawrence Lowlands are also attributed to Taconian compression. The first brittle deformation recognized in the Dunnage Zone and the Gaspé Belt is attributed to an ESE-WNW compression during the Acadian Orogeny. In the Dunnage Zone of southern Quebec, the Acadian paleostress axes are similar to the directions of σ1 axes and to the pure shear compressional regime computed for the Silurian and Devonian rocks of the Gaspé Belt. In the Gaspé Peninsula, the Acadian stresses are oriented ESE-WNW and are mechanically compatible with transpressional regimes. Reverse brittle faults and pure shear stress are identified along regional and secondary sets of NE-SW brittle faults, whereas a strike-slip stress regime is reconstructed along major east-west faults. In the Humber Zone of the Quebec Appalachians, a second compression is identified. It is characterized by conjugate ENE-WSW dextral and NW-SE sinistral strike-slip faults that crosscut Taconian thrust faults. This late deformation event is attributed to a distal expression of the Acadian Orogeny. 634Résumé : Les contraintes taconiennes et acadiennes reliées aux failles cassantes ont été reconstituées dans les Appalaches du Québec et du nord du Nouveau-Brunswick. La première phase de déformation cassante reconnue dans le domaine externe de la zone de Humber est associée à la tectonique plicative de faible profondeur de l'orogenèse taconienne. Elle est caractérisée par des failles cassantes N-S à NE-SO, inverses et conjuguées, formées en cisaillement pur (axes σ3 verticaux) sous des axes σ1 orientés ESE-ONO. Les failles de décrochement observées dans la plate-forme du Saint-Laurent sont aussi corrélées à la compression taconienne. La première phase de déformation cassante reconnue dans la zone de Dunnage et la Ceinture de Gaspé est attribuée à l'orogenèse acadienne et à une compression également orientée ESE-ONO. Dans la zone de Dunnage du sud du Québec, les paléocontraintes acadiennes reconstituées sont similaires aux directions des axes σ1 et au régime en cisaillement pur identifiés dans la Ceinture de Gaspé. En Gaspésie, les contraintes acadiennes sont orientées ESE-ONO et sont compatibles avec un régime en transpression. Des failles inverses et des contraintes en cisaillement pur sont reconnues le long des failles régionales et secondaires NE-SO, alors que des failles décrochantes et un régime en décrochement sont documentés le long des failles régionale...

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Section: Taconian Stress In the Humber Zone And St Lawrence Lowlandssupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Reconstruction of Taconian and Acadian paleostress regimes in the Quebec and northern New Brunswick Appalachians

Faure¹,

Tremblay²,

Malo³

2004

Can. J. Earth Sci.

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“…6d). Such successive stress patterns have also been recognized in the St Lawrence Lowlands and the Appalachian Belt (Gélard, Jébrak & Prichonnet, 1992;S. Faure, unpub.…”

Section: D Age Constraints On Reconstructed Tectonic Eventsmentioning

confidence: 70%

Brittle fault evolution of the Montréal area (St Lawrence Lowlands, Canada): rift-related structural inheritance and tectonism approached by palaeostress analysis

et al. 2003

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The Montréal area belongs to the St Lawrence Lowlands, a Cambrian Early Ordovician passive margin of the Iapetus Ocean, later covered by Appalachian Middle to Upper Ordovician foreland deposits. A structural and palaeostress analysis has been carried out in order to reconstruct its tectonic evolution. The structural map has been revised with new data. Palaeostresses are reconstructed based on inversion of fault slip data, and these results are independently corroborated by the microstructural study of calcite mechanical twinning. Field relationships are used to establish the relative chronology of fractures and to deduce the motion on regional faults. The reconstructed structural and tectonic evolution brings to light some relationships between structural inheritance and tectonic events that have affected the area since Early Palaeozoic times. An early NW–SE extension is responsible for N040-trending faults along the northern border of the St Lawrence Lowlands, and for N090- and N120-trending faults cross-cutting the Montréal area. This extension is followed by WNW–ESE and NNW compressions, which have induced reverse motion on pre-existing faults and generated strike-slip conjugate faults. Subsequent NE–SW and NNW–SSE-directed extensions have reactivated previous faults with normal to strike-slip motions. A late NE–SW compression is recorded in the Monteregian plutons. Compressions in WNW–ESE and NNW directions are consistent with Appalachian collisional tectonism, but N040- and N090-trending faults cross-cut Appalachian folds and foreland deposits. Although the early NW–SE extension is consistent with the collapse of the Iapetan margin in Early Palaeozoic times, most of the present geometry of the St Lawrence Lowlands could be attributed to Mesozoic tectonism, recorded as nearly N–S-directed extensional events.

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“…It is postulated that all deformations affecting Mississippian rocks of the Gaspé Peninsula are distal manifestations of the Hercynian-Alleghanian orogeny, which ended in the Permian, although later compressive features related to oceanic plate readjustments were also registered within Cretaceous rocks of southern Quebec, but indicate that 1 was northeast-southwest (Saull and Williams, 1974;Gélard et al, 1992;Faure et al, 1996b).…”

Section: Regional Perspective and Timing Constraintsmentioning

confidence: 99%

Alleghanian deformation in the eastern Gaspé Peninsula of Quebec, Canada

Jutras

Prichonnet

McCutcheon³

2003

Geo. Society Am. Bull.

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Juxtaposition of the Mississippian Ristigouche and Cannes-de-Roches Basins, which are subbasins of the composite late Paleozoic Maritimes Basin, occurred through dextral movement along the northwest-striking Percé Fault system in the eastern Gaspé Peninsula of Quebec. The northwest-striking faults are truncated by small north-northwest-striking dextral strike-slip faults, which probably developed as regional stress gradually rotated clockwise from north-northwest-south-southeast to northeast-southwest. This study provides the first evidence in eastern Quebec for significant post-Acadian block displacement other than normal faulting and indicates that Alleghanian deformation extended much farther north than previously thought. Identification of these structures formed during the Alleghanian orogeny but more than 1000 km away from areas of peak Alleghanian metamorphism in the southeastern United States underlines the far-reaching effects of continental collisions. It also casts doubt on the age attribution of brittle strike-slip faults elsewhere in the Gaspé Peninsula, away from Mississippian exposures. Such brittle faults were previously associated with late stages of the Acadian orogeny but could in fact be considerably younger.

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

Cited by 6 publications

References 19 publications

Reconstruction of Taconian and Acadian paleostress regimes in the Quebec and northern New Brunswick Appalachians

Reconstruction of Taconian and Acadian paleostress regimes in the Quebec and northern New Brunswick Appalachians

Brittle fault evolution of the Montréal area (St Lawrence Lowlands, Canada): rift-related structural inheritance and tectonism approached by palaeostress analysis

Alleghanian deformation in the eastern Gaspé Peninsula of Quebec, Canada

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