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TitleThe continent-ocean boundary at the rifted margin off eastern Canada: new results from deep seismic reflection studies
AuthorKeen, C E; de Voogd, B
SourceTectonics vol. 7, no. 1, 1988 p. 107-124,
Alt SeriesGeological Survey of Canada, Contribution Series 14387
Mediapaper; on-line; digital
File formatpdf
ProvinceEastern offshore region
AreaGrand Banks
Subjectstectonics; geophysics; structural geology; geophysical surveys; geophysical interpretations; seismic interpretations; seismic surveys; gravity surveys; magnetic surveys; continental crust; continental slope; unconformities; plate motions; plate tectonics; basins; subsidence; rifting; lithosphere; oceanic crust; Cretaceous; Mesozoic
Released2010 07 26
AbstractSeismic reflection data were collected and processed to 20 s two-way travel time along four lines which cross the rifted continent-ocean boundary off the Grand Banks region of eastern Canada specifically to examine the origin, age, and nature of this fundamental boundary. This represents the first regional study of its kind. The most important result is the presence of landward dipping reflectors near the foot of the continental slope. These occur where oceanic crust appears to terminate against the continent. We suggest that the dipping reflectors mark the continent-ocean boundary and that they may represent magmatic material which has underplated or intruded the rifted and thinned lower continental crust adjacent to the boundary. Sedimentary basins lie just landward of the continent-ocean boundary. Their subsidence history suggests significant heating and thinning of the lower lithosphere during rifting, and this may be an important stage leading to continental breakup. Rift basins formed further landward on the Grand Banks do not exhibit this thinning. Other significant seismic results include the presence of strongly reflective zones in the lower continental crust near the continent-ocean boundary. Also, the oceanic crust exhibits a complexity of reflections, some of which may be due to compositional zonation during magmatic crystallization. Finally, our results may have important consequences for continental predrift reconstruction, as oceanic crust appears to extend farther landward in the Newfoundland Basin than some recent studies have indicated.

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