| Titre | Hunting for Quaternary faults in eastern Canada: a critical appraisal of two potential candidates |
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| Auteur | Pinet, N; Lamontagne, M ; Duchesne, M J; Brake, V I |
| Source | Seismological Research Letters vol. 92, issue 2, 2020 p. 1102-1111, https://doi.org/10.1785/0220200322 |
| Liens | Erratum
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| Image |  |
| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20200506 |
| Éditeur | Seismological Society of America |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1785/0220200322 |
| Media | papier; en ligne; numérique |
| Formats | pdf; html |
| Province | Québec; Nouveau-Brunswick |
| SNRC | 11L; 11M; 12E; 12L; 21I; 21J; 21K; 21L; 21M; 21N; 21O; 21P; 22A; 22B; 22C; 22D; 22E; 22F; 22G; 22H; 22I; 22J; 22K; 22L |
| Région | Baie-Saint-Paul; Tadoussac; Fleuve Saint-Laurent; Péninsule de la Gaspésie; Île d'Anticosti; Sept-Îles; Golfe du Saint-Laurent |
| Lat/Long OENS | -71.5000 -63.8333 50.5000 46.6667 |
| Sujets | secousses séismiques; géologie du substratum rocheux; caractéristiques structurales; failles; topographie; escarpements; escarpements; levés géophysiques; levés sismiques marins; levés acoustiques marins;
bathymétrie; antécédents tectoniques; déplacement; Holocène; Zone sismique du bas du Saint-Laurent; Faille du Saint Laurent; géophysique; géologie marine; géologie structurale; tectonique; Sciences et technologie; Nature et environnement; Santé et
sécurité; Phanérozoïque; Cénozoïque; Quaternaire |
| Illustrations | cartes de localisation; cartes géolscientiques généralisées; profils sismiques; coupes transversales; images 3D |
| Diffusé | 2020 12 23 |
| Résumé | (disponible en anglais seulement)
This study documents two potential neotectonic features in the seismically active St. Lawrence estuary and western part of the Gulf of St. Lawrence of Quebec
(Canada). Historically, the region is the locus of series of damaging earthquakes, including the M 7 1663 earthquake, which suggests the occurrence of co-seismic ruptures beneath the St. Lawrence River. In the western Gulf of St. Lawrence (Lower St.
Lawrence seismic zone), a potential fault scarp identified on a vintage seismic profile has been investigated through high resolution seismic and multibeam bathymetry data. On the seafloor, the scarp corresponds to a ~ 1.8 m high (maximum) feature
that is located above a buried escarpment of the Paleozoic bedrock. Holocene units are draping over the escarpment on one profile, but are possibly cut on two others. The scarp meets several of the criteria generally associated with neotectonic
features. However, a close look at the data indicates that the staircase geometry of the top of the bedrock and its expression at surface are linked, at least partially, with the presence of an erosion-resistant unit. This makes a neotectonic
reactivation possible but not proven. In the Tadoussac area, ~ 40 km north of Charlevoix seismic zone, the offshore extension of the St-Laurent fault corresponds to a ~110 m high bathymetric escarpment with well-preserved triangular facets. Such
'fresh' morphology is unique in the St. Lawrence River Estuary and may attest to Quaternary displacements, yet other interpretations may also explain the unusual preservation of the escarpment. These two case studies illustrate the difficulty to
unambiguously document Holocene fault scarps, even in the marine domain where the sedimentary succession is generally continuous. |
| Sommaire | (Résumé en langage clair et simple, non publié)
La reconnaissance de failles ayant un aléa sismique est difficile, en particulier pour les domaines continetaux caractérisés par un taux
relativement faible de séismes importants. Dans cette étude, deux failles ayant potentiellement des déplacements quaternaires sont documentées. Ces failles rencontrent plusieurs critères généralement associés à des structures tectoniques 'récentes',
mais les déplacements quaternaires restent hypothétiques. |
| GEOSCAN ID | 327417 |
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