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TitleMass wasting on Alpha Ridge in the Arctic Ocean: new insights from multibeam bathymetry and subbottom profiler data
AuthorBoggild, K; Mosher, D CORCID logo; Travaglini, P; Gebhardt, C; Mayer, L
SourceGeological Society, Special Publication vol. 500, no. 1, 2020 p. 323-340,
Alt SeriesNatural Resources Canada, Contribution Series 20190297
PublisherGeological Society of London
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthern offshore region
AreaAlpha Ridge; Arctic Ocean
Lat/Long WENS-125.0000 -90.0000 88.0000 85.0000
Subjectsmarine geology; surficial geology/geomorphology; geophysics; Nature and Environment; Science and Technology; marine sediments; landslides; mass wasting; slope failures; landslide deposits; collapse structures; deformation; bathymetry; seafloor topography; geophysical surveys; acoustic surveys, marine; earthquakes
Illustrationslocation maps; tables; stratigraphic columns; geophysical profiles; geoscientific sketch maps; profiles
ProgramDelineating Canada's Continental Shelf Under UNCLOS
Released2020 05 13
AbstractMarine geological and geophysical data from Alpha Ridge in the Arctic Ocean are sparse because of thick perennial sea-ice cover which prevents access by most surface vessels. Rare seismic data in this area, acquired largely from drifting ice-camps, had shown the hemipelagic drape that covers most of the ridge is highly disrupted within a large (> 90 000 km2) south central region. Here, evidence of pronounced seafloor erosion and debris flows infilling seafloor lows was previously interpreted to be the result of a possible bolide impact. In recent years, several icebreaker expeditions have successfully acquired multibeam bathymetry and subbottom profiler data in the western segment of this region. Analysis of these data reveals a complex seafloor morphology characterized by ridges and troughs, angular blocks, and escarpments as well as seismic facies characterized by hyperbolic seafloor reflections, and convoluted to incoherent and transparent subbottom reflectivity. These features are interpreted as evidence of sediment mass movement with varying degrees of lateral transport deformation. At least two episodes of failure are interpreted based on the presence of both buried and surficial mass transport features. As multiple events are interpreted, seismicity is considered to be the most plausible trigger mechanism rather than bolide impact.
Summary(Plain Language Summary, not published)
The Alpha Ridge is a large submerged platform within one of the least explored areas of the Arctic Ocean. It is under-explored because of thick year-round sea-ice cover that limits access to the area. Early exploration from ice-camps and the first icebreaker visits showed that the seafloor along the shallowest parts of the ridge was exceptionally complex. It was interpreted that there were extensive underwater landslides in the area that were the result of an asteroid impact. Recent icebreaker expeditions collected new seafloor images that show the structure of the sediments at and under the seabed. These new data confirm the presence of features formed by underwater landslides, and show that multiple episodes of landsliding has occurred. This evidence suggests a recurring trigger mechanism, such as earthquakes along Alpha Ridge, is the most likely cause of these landslides (rather than a single event like an asteroid impact).

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