GEOSCAN, résultats de la recherche


TitreDipping shear zones and the base of the crust in the Appalachians, offshore Canada
AuteurHall, J; Quinlan, G; Marillier, F; Keen, C
SourceSeismic probing of continents and their margins; Tectonophysics vol 173, no 1-4, test, 1990 p. 581-593,
Séries alt.Commission géologique du Canada, Contributions aux publications extérieures 24089
Séries alt.Lithoprobe Publication 96
Séries alt.International Lithosphere Program Contribution 154
ÉditeurElsevier BV
RéunionInternational Meeting on Seismic Probing of Continents and their Margins; Canberra; AU; 19880701; juillet 1-8, 1988
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceRégion extracotière de l'est
Sujetslevés géophysiques; levés sismiques marins; marges continentales; failles; zones de cisaillement; zones orogéniques; océanographie; tectonophysique; lithosphère; gscconts |e Geological Survey of Canada, Contribution Series |f Commission géologique du Canada, Contributions aux publications extérieures; lithcont |e Lithoprobe Publication |f Lithoprobe Publication; ilithopc |e International Lithosphere Program Contribution |f International Lithosphere Program Contribution; géologie structurale; géophysique
Illustrationssketch maps; seismic profiles
Résumé(disponible en anglais seulement)
The Seismological character of the Appalachian mobile belt offshore from eastern Canada includes an unusual concentration of northwest-dipping reflectors which appear to dip through sub-horizontal reflectors at the base of the crust. The geometry of these structures has been characterised by ray-trace migration. They are not point diffractors. They appear to dip at between 25 and 45°, but flatten upwards towards a mid-crustal "bright" band and disappear downwards into the mantle. We interpret the reflectors as shear zones which ramp through the lower crust from a mid-crustal detachment to a diffuse and less reflective set of shears in the mantle. It is suggested that the reflectors were caused by the collision of continental blocks at the final closure of the Iapetus Ocean, but may have been subject to later reactivation, especially during late Carboniferous strike-slip.