Geological Survey of Canada Offshore Grain Size Analyses, Beaufort Shelf and Slope - Expedition Database
Ship: CCGS Amundsen CA
Principal Investigator: Steve Blasco
Start Date: 01-01-2009
End Date: 31-03-2015
Citation: Geological Survey of Canada Offshore Grain Size Analyses, Beaufort Shelf and Slope - Expedition Database: Unpublished data
Abstract: Grain size is a fundamental means of characterizing seabed sediment. Seabed sediment may be named according to its grain size. Grain size analysis of marine sediment samples is a valuable method of determining: the source of the sediments (e.g. whether they were derived from land and blown out to sea; whether they were deposited by oceanic currents or delivered by glaciers or icebergs); the energy level at the seabed under modern conditions (e.g. is it quiet enough for fine-grained sediments to be deposited or are fines winnowed away leaving only coarser-grained sands and gravels behind?); the energy level in the past when sediments below the seabed were deposited, based on down-core analysis of grain-size; the strength and stability properties of the sediments and their response to loading. Sands, clays and silts all behave very differently under loads. Even a small amount of fines can make a sediment unstable so grain size is a crucial part of doing a geotechnical investigation of soil stability. The same applies for assessing the stability of a slope under wave-, or sediment- or seismic- loading; the potential for pollutants or contaminants to be deposited or transported; to determine whether sediments will be eroded and or transported under the effects of bottom currents that may be produced during tidal fluctuations or severe winter storms. Analysis generally follows different techniques, both with evolution of laboratory technology and with different samples. Sands and gravels are generally are treated differently than muds (fines). Seiving of the coarser fraction is now being replaced with automated optical recognition while coulter counter technique is common for the fine fraction. The supplied url navigates the user to the GSC "Expedition Database" which houses metadata on all GSC marine expeditions, including BREA - related Expeditions (cruises). BREA - specific expeditions are limited to numbers 2009804, 2010804, 2011804 and 2014804. The user can navigate to "Obtain Grain Size Data by Expedition of Bounding Coordinates" under "Analysis". This provides the user with coarse fraction results. If applicable, a more detailed size classification of the fine fraction is available though a GSC request. Grain size is a basic analytical tool used to further scientific research in the areas of sedimentology and paleoceanography. Grain size influences the mobility, stability and physical properties of sediment, has an important impact on the associated biota, and can be used to interpret the origin and behavior of seabed sediment.