CGRG Bibliography of Canadian Geomorphology
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Author : Gagne, H.; Lajeunesse, P.; St-Onge, G.; and Bolduc, A.
Date : 2008.
Title : Late-Quaternary marine geomorphology of the Trois-Pistoles-Forestville area, St. Lawrence Estuary (Québec).
Publication : Quebec 2008: 400 Years of Discoveries. Joint Meeting of the Geological Association of Canada, Mineralogical Association of Canada, Society of Economic Geologists and the Society for Geology Applied to Mineral Deposits. May 26-28, 2008. Québec City Convention Centre, Québec.
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Abstract
Here we report on the geomorphological and sedimentary processes that shaped the seafloor of the Trois-Pistoles-Forestville area (Lower St. Lawrence Estuary) since the retreat of the Laurentide Ice Sheet (12 ka–13 ka BP) based on the analysis of high resolution multibeam sonar data, acoustic subbottom (Chirp) profiles and sediment cores. Since deglaciation, glaciomarine and postglacial deposits were intensely remobilised by many mass movement events. Because these mass movement features are located near the Charlevoix-Kamouraska seismic zone, most of them were probably seismically induced. Slides, debris flows and turbidity currents produced failure surfaces, channels as well as submarine canyons and fans on the coastal shelves and along the northern and southern flanks of the Laurentian Channel and deposited important volumes of sediments on its bottom. On the southern coastal shelf of the Estuary, a failure surface of 15-20 m high occurs between depths of 40 and 80 m. The eastern portion of this surface is dominated by slides, while its western portion is dominated by debris flows. The northern coastal shelf is characterized by pockmarks, ruptures within the sediments and channels located offshore the Sault-aux-Cochons River mouth. Canyons and failure surfaces are observed on the slope between the northern coastal shelf and the Laurentian Channel. Chirp profiles also allowed the identification of ice-distal and ice-proximal glaciomarine units. However, glacial geomorphic features were not observed in the study area and glaciomarine deposits are mostly buried under a generally thick postglacial unit. A paraglacial unit, deposited during the construction of deltas on the north shore and prior to the deposition of the postglacial unit, was only observed on the northern coastal shelf.
Bibliography of Canadian Geomorphology