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TitleMultiple failure styles related to shallow gas and fluid venting, upper slope Canadian Beaufort Sea, northern Canada
AuthorSainte-Ange, F; Kuus, P; Blasco, S; Piper, D J W; Hughes-Clarke, J E; MacKillop, K
SourceMarine Geology vol. 355, 2014 p. 136-149,
Alt SeriesEarth Sciences Sector, Contribution Series 20130177
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthern offshore region
AreaBeaufort Sea
Lat/Long WENS-136.7500 -135.7500 70.6667 70.3833
Subjectsmarine geology; fossil fuels; surficial geology/geomorphology; hydrocarbons; hydrocarbon potential; gas; hydrate; gas seeps; slope deposits; slope failures; slope stability; permafrost; bathymetry; seabottom topography; seafloor topography; submarine features; marine deposits; marine sediments; Cenozoic; Quaternary
Illustrationslocation maps; profiles; photographs
ProgramMarine Geohazards, Public Safety Geoscience
AbstractThe continental slope of the Canadian Beaufort Sea presents an exceptional opportunity to study the relationship between the fluid venting and the formation of mass-transport deposits. The continental shelfwas emergent and partially ice-free during the last glaciation and is underlain bywidespread permafrost.Water-columnbackscatter has shown the locations of more than 40 active gas vents along seaward margin of the subsea permafrost at the shelf break and upper slope. New multibeam bathymetry and subbottom profiler data show shallow potentially late Holocene failures and mass-transport deposits on the upper slope. Upslope from a prominent headscarp, undulating seabed with apparent growth faults overlies an acoustically incoherent to stratified horizon at 50 m sub-bottom interpreted as a decollement surface over which progressive creep has occurred. Similar creep is present in places on the upper slope and in places seems to have evolved into small translational slides, involving more compacted sediment buried N25 m, or intomuddy debris flowswhere sediments buried b25mhave failed. Much of the slope failed during a regional retrogressive event, the Ikit slump, likely initiated on steep channel walls on the lower slope. Characteristic ridge and trough morphology resulting from retrogressive spreading or rotational slumping are preserved on gradients b2° on the upper slope, but appear to have been completely evacuated on gradients of 3° on the mid slope, where muddy debris-flow deposits are found. Correlations between radiocarbon dated cores and sub-bottom profiles show that the retrogressive failure occurred in the last 1000 years. This study implies that Holocene shelf break and upper slope stability in the Beaufort Sea are strongly linked to the dynamics of the permafrost and the presence of weak, gas-rich sediments. It demonstrates that creep deformation evolves into either muddy debris flows or translational slides, dependent on sediment strength.
Summary(Plain Language Summary, not published)
This paper describes the various styles of submarine landslides on the upper Beaufort Slope and interprets the character of deformation and movement. It makes observations on the spatial relationship of seafloor fluid (mostly gas) vents and the distribution of landslide features. The paper does NOT make observations on the hazards posed by these landslides nor their recurrence interval.