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TitleGeomorphological characteristics and variability of Holocene mass-transport complexes, St. Lawrence River Estuary, Canada
AuthorPinet, N; Brake, V; Campbell, CORCID logo; Duchesne, M
SourceGeomorphology vol. 228, 2015 p. 286-302,
Alt SeriesEarth Sciences Sector, Contribution Series 20140152
PublisherElsevier BV
Mediapaper; on-line; digital
File formatpdf
NTS21M/09; 21M/16; 21N/05; 21N/11; 21N/12; 21N/13; 21N/14; 22B/12; 22B/13; 22B/14; 22B/15; 22C; 22F/01; 22F/02; 22F/08; 22G/02; 22G/03; 22G/04; 22G/05; 22G/06
AreaSt. Lawrence River
Lat/Long WENS -70.7500 -66.5000 49.5000 47.2500
Subjectsgeophysics; general geology; marine geology; surficial geology/geomorphology; sediment transport; landslides; bathymetry; morphology; St-Lawrence Estuary; submarine landslides; seafloor instability; Holocene
Illustrationslocation maps; bathymetric profiles; seismic reflection profiles; 3-D models; tables; graphs; histograms
ProgramOffshore Geoscience, Geoscience for East Coast Offshore Developments
AbstractRecently acquired multibeam bathymetry data are used to investigate seafloor instability features along a 310 km-long segment of the St. Lawrence River Estuary. The analysis of this dataset indicates that submarine slides occur over a much larger area than previously recognized and that Holocene sediments are reworked by mass-transport along significant portions of both the northwest and southeast margins of the Laurentian Channel. In the surveyed area, 96 individual mass-transport complexes (MTCs) were identified representing 13% of the seabed. MTCs vary in area from less than 1 km2 to more than 40 km2 and exhibit various geomorphological signatures. Qualitative observation reveals an apparent disparity between MTCs that remain coherent and those that disintegrate during downslope transport evolving into a blocky morphological signature. For allMTCs, morphological parameters have been measured (area, length, and height) or calculated (slope and roughness). This quantitative analysis provides a unique opportunity to study these parameters in a statistically significant and homogeneous dataset located in a relatively small area that experienced a similar Quaternary history. In many cases, mass transport events appear to initiate in the vicinity of steep bedrock walls located along some segments of the estuary. The timing of mass-transport events was not constrained during this study. However, the fact that the region hosts the Charlevoix seismic zone, the most tectonically active area in eastern Canada, strongly suggests that earthquakes acted as a trigger for submarine landsliding.
Summary(Plain Language Summary, not published)
This study, based mainly on high-resolution bathymetric data, presents the results of submarine landslide mapping in the St. Lawrence Estuary. Ninety six landslides represent 13% of the Estuary seafloor. A special focus is given on the diverse morphological characteristics of landslides. Preconditioning factors (including earthquakes) are reviewed. Even if not formally discussed, risks associated with submarine landslides in this highly populated area appear clearly when reading the paper.

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