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TitleSpatial trends of seismic velocity within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge: Evidence for accelerated porosity reduction?
AuthorShimeld, J; Li, Q; Chian, D; Lebedeva-Ivanova, N; Jackson, RORCID logo; Mosher, DORCID logo; Hutchinson, D
Source7th International Conference on Arctic Margins, ICAM 2015 [abstracts]; Norges Geologiske Undersøkelse, Rapport 2015.032, 2015 p. 130 Open Access logo Open Access
LinksOnline - En ligne (full volume - volume complet, PDF, 4.42 MB)
Alt SeriesEarth Sciences Sector, Contribution Series 20160144
PublisherGeological Survey of Norway
MeetingICAM 2015 - Seventh International Conference on Arctic Margins; Trondheim; NO; June 2-5, 2015
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthern offshore region
NTS98C; 98F; 98G; 99B; 99C; 99D; 107E; 107F; 107G; 107H; 117E; 117F; 117G; 117H
AreaArctic Ocean; Mackenzie Delta; Banks Island; Prince Patrick Island
Lat/Long WENS-180.0000 -120.0000 87.5000 70.0000
Subjectsgeophysics; marine geology; regional geology; stratigraphy; surficial geology/geomorphology; mathematical and computational geology; geophysical surveys; seismic reflection surveys; seismic refraction surveys; seismic surveys, marine; acoustic surveys, marine; crustal structure; oceanic crust; sedimentary basins; continental margins; continental shelf; continental slope; abyssal plains; submarine fans; bedrock geology; lithology; sedimentary rocks; shales; sandstones; turbidites; marine sediments; glaciomarine deposits; modelling; porosity; thermal analyses; heat flow; burial history; magnetic anomalies; geological history; bathymetry; submarine ridges; Canada Basin; Alpha-Mendeleev Ridge; Nautilus Basin; Stefansson Basin; Mackenzie Fan; Beaufort-Mackenzie Margin; Alaska Margin; Northwind Ridge; Chukchi Plateau; Sever Spur; Colville River; Mackenzie Trough; Amundsen Gulf Trough; M'Clure Strait Trough; Laurentide Ice Sheet; Phanerozoic; Cenozoic; Quaternary; Tertiary; Mesozoic; Cretaceous; Jurassic
ProgramDelineating Canada's Continental Shelf Under UNCLOS
Released2015 11 09
AbstractThe Canada Basin and southern Alpha-Mendeleev Ridge underlie a significant proportion of the Arctic Ocean, but the geology of this remote, undrilled, and mostly ice-covered frontier is poorly known. Valuable new information is encoded in seismic wide-angle reflections and refractions on expendable sonobuoy records acquired between 2007 and 2011. Velocity-depth measurements of the sedimentary succession are extracted from published analyses of the records for 142 sonobuoy stations distributed irregularly across an area of 1.9E+06 km2. The measurements are modelled at regional, subregional, and station-specific scales using an exponential function of inverse velocity with geologically meaningful parameters that are determined through conventional numerical regression techniques. With this approach, smooth, non-oscillatory velocity-depth estimates can be generated for any desired location in the study area, even where the measurement density is low. The results comprise a useful comparative reference for global studies of seismic velocity, burial history, sedimentary compaction, seismic inversion, and overpressure prediction, particularly in mudrock-dominated successions. Sedimentary thickness in the Canada Basin and southern Alpha Ridge is obtained from seismic reflection horizons interpreted in the time domain and converted to depth using the velocity-depth estimate for each seismic trace. Mapping of the observed-to-predicted velocities at regional, subregional, and station-specific scales reveals systematic trends associated with: the Mackenzie fan; the continental slopes beyond the Mackenzie fan; the abyssal plain; the southwestern Canada Basin; and, the Alpha-Mendeleev magnetic domain. These trends are largely attributable to changes in lithology with distance from the ancestral Mackenzie River, which is confirmed to be the predominant sedimentary source. However, lithological factors do not account fully for the elevated trends of seismic velocity found in the southwestern Canada Basin and the Alpha-Mendeleev magnetic domain. A plausible additional factor in these subregions is accelerated porosity reduction, perhaps due to volcanism-related hydrothermal alteration.
Summary(Plain Language Summary, not published)
The Canada Basin and southern Alpha-Mendeleev Ridge underlie a significant proportion of the Arctic Ocean but, since there are no deep boreholes, the geology of this remote, mostly ice-covered region is poorly understood. Geophysical measurements of the speed of seismic waves travelling within the Earth provide insight into the nature and thickness of the sedimentary rocks within an area of nearly 2 million square kilometres. Geological processes affecting the sedimentary rocks, such as compaction and the flow of heat through the crust, are inferred by constructing 3-D spatial models of the data set.

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