scholarly journals Multichannel Seismic Reflection Profiles Across the Vancouver Island Continental Shelf and Slope

1991 ◽  
Author(s):  
G D Spence ◽  
R D Hyndman ◽  
S Langton ◽  
C J Yorath ◽  
E E Davis
Keyword(s):  
Continental Shelf ◽  
Seismic Reflection ◽  
Vancouver Island ◽  
Multichannel Seismic Reflection ◽  
Seismic Reflection Profiles

Seismic reflection constraints on imbrication and underplating of the northern Cascadia convergent margin

1996 ◽  
Vol 33 (9) ◽  
pp. 1294-1307 ◽  
Author(s):  
A. J. Calvert
Keyword(s):  
Continental Shelf ◽  
Seismic Reflection ◽  
Deep Structure ◽  
Vancouver Island ◽  
Cascadia Subduction Zone ◽  
Accretionary Wedge ◽  
Seismic Profiles ◽  
Outer Continental Shelf ◽  
E Region ◽  
Seismic Reflection Profiles

An interpretation of the deep structure of the continental shelf offshore southern Vancouver Island, subject to constraints from other geophysical data, is derived by combining seismic reflection profiles shot in 1989 with those from an earlier 1985 survey. Accretionary wedge sediments, which extend landward beneath the volcanic Crescent terrane, comprise two primary units, both of which have shortened through duplex formation. The maximum thickness of the Crescent terrane, 6–8 km, occurs just seaward of its contact with the inboard, largely metasedimentary Pacific Rim terrane. The E region of reflectivity, first detected dipping landward beneath Vancouver Island, is regionally extensive, being observed on all the seismic profiles. The E reflectivity thins seaward and splits into two or more strands that probably link into major faults within the accreted sedimentary wedge. Reflections from the interplate décollement beneath the outer continental shelf separate from the downgoing plate, continue into the deepest level of the E reflectivity, and are interpreted to represent a single décollement surface above which imbrication of accreted units occurred. It is proposed that at the southern end of Vancouver Island the E reflections represent mainly underthrust sediments above a former subduction décollement, both of which were incorporated into the overlying continent when the subduction thrust stepped down into the descending oceanic plate. This change in depth of the subduction thrust underplated one or more mafic units to the continent. The reflection from the top of the subducting Juan de Fuca plate appears to be around 5 km shallower farther north along the margin, indicating that the underplated region could be confined to the embayment in the Cascadia subduction zone.

scholarly journals Interpretation of shallow seismic profiles over the continental shelf in West Greenland between latitudes 64° and 69°30'N

1980 ◽  
Vol 100 ◽  
pp. 58-61
Author(s):  
E.F.K Zarudzki
Keyword(s):  
Continental Shelf ◽  
Seismic Reflection ◽  
Preliminary Report ◽  
Early Stage ◽  
Sidescan Sonar ◽  
Seismic Profiles ◽  
West Greenland ◽  
Shallow Seismic ◽  
Seismic Reflection Profiles

The work included the study of parts of the data obtained during the survey cruise WESTMAR 78, described in a preliminary report (Brett & Zarudzki, 1979). The data consist of 10 741 km seismic reflection profiles obtained with sparker, sub-bottom, airgun and boomer systems; 8474 km of bathymetric profiles, 3894 km of sidescan sonar profiles and 8545 km of magnetic profiles. The study objectives in the area and its subdivision were established at an early stage.

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