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TitleDistribution of seabed ice scour caused by grounded icebergs on the Canadian Baffin continental margin
AuthorBennett, R; Campbell, C; Hughes-Clarke, J; Hynes, S; Fitzgerald, C
SourceArcticNet (ASM2012), programme; 2012 p. 33
LinksOnline - En ligne (Programme, PDF 3 MB)
Year2012
Alt SeriesEarth Sciences Sector, Contribution Series 20130333
PublisherArcticNet
Meeting2012 ArcticNet Annual Science Meeting; Vancouver; CA; December 11-14, 2012
Documentbook
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceOffshore region
NTS27A; 27D; 27E; 27G; 27H; 28; 38A; 38D; 38E; 38F; 38G; 38H
AreaBaffin Bay
Lat/Long WENS -80.0000 -55.0000 78.0000 68.0000
Subjectsmarine geology; geophysics; Pleistocene; echo sounding; ice scours; scouring; scour marks; sea level changes; Quaternary
ProgramNational-Scale Geohazard Assessments, Public Safety Geoscience
AbstractMultibeam echosounder data have been used to map the distribution of ice scour on the Canadian Baffin Shelf. The data were collected by the Ocean Mapping Group at the University of New Brunswick (OMG-UNB) during ArcticNet and CASES expeditions onboard the CCGS Amundsen from 2003 to 2011. Using the multibeam data set gridded at 25 m horizontal resolution, ice scour was observed in water depths up to 850 m. Scours typically have an incised depth of 1 - 4 m into the seabed but can occasionally be greater than 4 m with the maximum scour depth observed to date being 19 m. The width of the scours typically ranges from ~65 m across up to ~500 m across. Due to the incomplete multibeam coverage it is difficult to measure the length of the scours as the start and end points are typically not visible. The scours that do have large sections imaged in the multibeam data set are several tens of kilometres long.
Modern-day icebergs in Baffin Bay usually have drafts between 100 and 200 meters for the larger icebergs but occasionally can be much deeper. The deepest ice keel observed in Northern Baffin Bay destroyed acoustic monitoring equipment on the seabed in 427 m of water during the 1967-1968 ice season. These extreme icebergs generate seabed ice scour to depths of ~430 m however they cannot account for the relict scour population observed on the Canadian Baffin Shelf in water depths greater than ~430 m. Relict iceberg scours are scours that occur in areas where icebergs are no longer found, or in areas where icebergs can no longer reach the seabed due to an increase in water depth or a decrease in iceberg size. Iceberg scour has been identified using the OMG-UNB multibeam data set to depths of 850 m water depth in Baffin Bay and other studies have observed features that might be interpreted as ice scour at depths over 1000 m on the Greenland side of Baffin Bay. While the age of these scours is unknown, their occurrence in water depths beyond what can be scoured by the modern-day iceberg regime and their superposition on glacial sediments suggest that they were likely formed during deglaciation of Late Pleistocene ice shelves and ice sheets. During the Late Pleistocene, sea level would have been up to 120 m below present and icebergs calving from the large ice sheets and ice shelves in the area would have been larger than those observed at present.
Using observations from the data available at present, modern-day icebergs are capable of scouring to water depths of ~430 m in Baffin Bay. Ice scours in water depths greater than 430 m are likely relict features; some being formed more than ~9,000 years ago.
Summary(Plain Language Summary, not published)
Multibeam echosounder data were used to map the distribution of ice scour in Baffin Bay. Ice scours observed in Baffin Bay can either be relict features (formed during the last glaciation when sea level was lower and icebergs were larger) or formed during the present-day. Using observations from the data available at present, modern-day icebergs are capable of scouring to water depths of ~430 m in Baffin Bay. Ice scours in water depths greater than 430 m are likely relict features; some being formed more than ~9,000 years ago.
GEOSCAN ID293339