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TitleFirst results on velocity analyses of multichannel seismic data acquired with the icebreaker RV Araon across the southern Beaufort Sea, offshore Yukon
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AuthorRiedel, M; Hong, J K; Jin, Y K; Rohr, K M M; Côté, M M
SourceGeological Survey of Canada, Current Research (Online) 2016-3, 2016, 27 pages, https://doi.org/10.4095/298840
Year2016
PublisherNatural Resources Canada
Documentopen file
Lang.English
Mediadigital; on-line
File formatpdf
ProvinceNorthern offshore region
AreaBeaufort Sea; Beaufort Sea shelf; Beaufort Sea slope
Lat/Long WENS-147.0000 -131.0000 72.0000 69.0000
Subjectsgeophysics; fossil fuels; geophysical surveys; seismic interpretations; seismic surveys; seismic surveys, marine; seismology; seismic waves; gas; seismic velocities; velocity surveys; hydrate; permafrost; freezing ground; ground ice; bathymetry; continental shelf; continental slope; slope deposits; Mackenzie Trough
Illustrationslocation maps; tables; profiles; logs
ProgramMarine Geohazards, Public Safety Geoscience
Released2016 09 29
AbstractOne thousand two hundred twenty kilometres of multichannel seismic data were acquired in the Beaufort Sea in 2013 and 2014 to interpret shallow sedimentary structures associated with the upper Cenozoic Iperk and Shallow Bay depositional sequences. Seismic velocity analyses suggest a remarkably consistent regional velocity-depth trend on the slope within the upper 4 s two-way traveltime. A separate velocity trend was not defined beneath the shelf in this region, where data are influenced by the occurrence of permafrost. Deviations from this trend were noted at unconformities including an upper erosional unconformity.
The seismic data in the Mackenzie Trough region suggest a different velocity-depth trend within the upper section and the region is marked by a large erosional unconformity, likely the base of the Shallow Bay sequence. Velocity analyses suggest the removal of up to 425 m of overburden; however, this is an overestimate of erosion as differential compaction from the glacial history has not yet been taken into account. In deeper water (>750 m) a bottom-simulating reflector is present, characterized by the occurrence of free gas and a low-velocity zone.
Analyses of three fluid-expulsion features on the slope indicate that the Pokak fluid-expulsion feature and the Triple-Mound fluid-expulsion feature are linked to underlying anticline structures. A flat-topped fluid-expulsion feature at the flank of an equivalent anticline was also examined, but the occurrence of shallow gas creates a blank zone beneath this structure. Pronounced changes in the velocity-depth function at these fluid-expulsion features are linked to occurrence of free gas, and/or fluidized mud extrusions.
Summary(Plain Language Summary, not published)
1,220 line km of multichannel seismic data were acquired in the Canadian Beaufort Sea during a 2014 research cruise in collaboration with the Korea Polar Research Institute. Seismic lines were acquired to map the shallow sedimentary structures. Seismic velocity analyses suggest a consistent regional velocity-depth trend on the slope, east of the Mackenzie Trough, with deviations noted at an upper erosional unconformity associated with mega-scale glacial lineations and at the base of the Shallow Bay Formation. Data acquired in the Mackenzie Trough region suggest a different velocity-depth trend, with the region being marked by a large erosional unconformity. Velocity analyses suggest a removal of up to 600 m of overburden. In deeper water, a bottom-simulating reflector is characterized by the presence of free gas and a low velocity zone. The data allowed analyses of fluid expulsion features and determine that the source of mud extruded on the seafloor was from depths of up to 3 km.
GEOSCAN ID298840