| Title | Storm-induced turbidity currents triggered in the absence of shelf sediment supply |
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| Author | Normandeau, A ;
Bourgault, D; Neumeier, U; Lajeunesse, P; St-Onge, G; Gostiaux, L; Chavanne, C |
| Source | ISC2018 - 20th International Sedimentological Congress, abstract volume; 2018 p. 1 |
| Image |  |
| Year | 2018 |
| Alt Series | Natural Resources Canada, Contribution Series 20180228 |
| Publisher | IAS |
| Meeting | ISC2018 - 20th International Sedimentological Congress; Québec, QC; CA; August 13-17, 2018 |
| Document | Web site |
| Lang. | English |
| Media | paper; digital |
| File format | pdf |
| Province | Quebec; Eastern offshore region |
| NTS | 22G/03; 22G/04; 22G/05; 22G/06 |
| Area | Pointe-des-Monts; St. Lawrence River |
| Lat/Long WENS | -67.6500 -67.0667 49.3000 49.0333 |
| Subjects | marine geology; surficial geology/geomorphology; sedimentology; geophysics; marine environments; turbidity currents; storms; continental shelf; submarine canyons; geophysical surveys; acoustic surveys,
marine; side-scan sonar; bathymetry; sedimentary structures; bedforms; cyclic processes; sediment dispersal; dispersal patterns; temperature |
| Program | Public Safety
Geoscience Marine Geohazards |
| Released | 2018 08 01 |
| Abstract | 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. |
| Summary | (Plain Language Summary, not published)
Turbidity currents were recorded in the Pointe-des-Monts canyons using current profilers and were shown to be triggered during major storms affecting
eastern Canada. |
| GEOSCAN ID | 311310 |
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