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TitreStorm-induced turbidity currents triggered in the absence of shelf sediment supply
AuteurNormandeau, A; Bourgault, D; Neumeier, U; Lajeunesse, P; St-Onge, G; Gostiaux, L; Chavanne, C
SourceISC2018 - 20th International Sedimentological Congress, abstract volume; 2018 p. 1
Année2018
Séries alt.Ressources naturelles Canada, Contribution externe 20180228
ÉditeurIAS
RéunionISC2018 - 20th International Sedimentological Congress; Québec, QC; CA; août 13-17, 2018
Documentsite Web
Lang.anglais
Mediapapier; numérique
Formatspdf
ProvinceQuébec; Région extracotière de l'est
SNRC22G/03; 22G/04; 22G/05; 22G/06
Lat/Long OENS -67.6500 -67.0667 49.3000 49.0333
Sujetsmilieux marins; courants de turbidite; tempêtes; plate-forme continentale; canyons sous-marins; levés géophysiques; levés acoustiques marins; sonar latéral; bathymétrie; structures sédimentaires; configurations lit; processus cycliques; dispersion des sédiments; profils de dispersion; temperature; géologie marine; géologie des dépôts meubles/géomorphologie; sédimentologie; géophysique
ProgrammeRisques géo marines, Géoscience pour la sécurité publique
Diffusé2018 08 01
Résumé(disponible en anglais seulement)
The monitoring of turbidity currents allows a better understanding of their behaviour and timing in relation to triggering events. The triggers of turbidity currents often remain hypothetical since very few studies have directly observed them. These triggers are nearly always inferred, even when monitoring is present. In this study, the Pointe-des-Monts submarine shelf canyons were monitored using Acoustic Doppler Current Profilers (ADCPs) and repeated high-resolution swath bathymetry mapping. Repeated mapping revealed that crescent-shaped bedforms, interpreted as cyclic steps, migrated upslope during the last 10 years, despite the absence of sediment on the shelf or river inflow in the region. During the winter of 2017, an intense turbidity current, with velocities reaching 2 m s-1, was recorded and appears to be responsible for the migration of cyclic steps. This turbidity current was coincident with one of the greatest storm of the year that generated 3.8 m waves along the coastline of the region. The turbidity current temperature in combination with repeated seafloor mapping suggest that it was triggered at depths of > 100 m and that it is not attributed to a canyon-wall failure. Three other turbidity currents, albeit weaker, were also triggered during storms during the winter of 2016-2017. These results demonstrate that storms can possibly trigger turbidity currents at deeper water depths than the shelf, although the exact process by which sediments are put in suspension remains enigmatic.
Résumé(Résumé en langage clair et simple, non publié)
Des courants de turbidité ont été enregistrés à Pointe-des-Monts en utilisant des profileurs de courant et ont été déclenchés durant des tempêtes qui ont affecté l'est du Canada.
GEOSCAN ID311310