Benthic substrates of the Saguenay fjord, the St. Lawrence lower estuary and Gulf

Description of the submarine morphology and characteristics of the sediments (lithology, grain size, mineralogy, and chemistry) of the Saguenay fjord, the lower Estuary and Gulf of St. Lawrence.

The layer contains a synthesis of geological and geochemical data collected and interpreted over 10 years and is accompanied by detailed bathymetric and surface sediment maps. Most of this study deals with the geomorphology, surface sediments (lithology, mineralogy, and chemistry), and present depositional conditions, but several studies have also been made of the bedrock geology and the stratigraphy of the unconsolidated sediments.

Purpose

These studies are regional and of a reconnaissance nature in the sense that they have been designed to obtain acoustical and sampling data on the morphology and basic properties of the sediments from the whole Gulf. This approach was used to provide a broad appraisal of the sedimentary environment of the Gulf and its late-glacial and postglacial history.

Additional Information

Unknown date of numeric version.

Acoustical and sampling data were obtained in the River and Gulf of St. Lawrence on board of different boats over the years. Sounding lines and sample stations were selected initially on the basis of submarine morphology and later in combination with a preliminary sedimentological map as the sea floor data accumulated.

More specifically, acoustical data on the topography and nature of the sea floor was obtained from echosounding and continuous seismic profiling. Sounding records were studied, interpreted, and reduced manually in most cases to a scale suitable for plotting and presentation. The information on the continuous seismic records was first interpreted visually and the reduced to constant scale with the aid of a pantograph with independently vertical and horizontal scales.

Also, about 1500 sediments samples have been collected from various parts of the Gulf to obtain a regional coverage of the sedimentary environment in the area. The sediment sample were sorted and split after their water content had been determined. Mineralogical analyses were carried out after separation into a heavy and light fraction. The light minerals were identified by a combined method of staining and the use of immersion liquids.

For more details on consulted documents and their limit, see the following report:

Loring, D. H., and D. J. G. Nota. 1973. Morphology and sediments of the Gulf of St. Lawrence. Bull. Fish. Res. Bd. Can. 182. 147 p. + 7 charts.