GEOSCAN, résultats de la recherche


TitreThe crustal structure of the Alpha Ridge at the transition to the Canadian Polar margin - results from a seismic refraction experiment
AuteurFunck, T; Jackson, H R; Shimeld, J
SourceJournal of Geophysical Research vol. 116, issue B12, B12101, 2011 p. 1-26, (Accès ouvert)
Séries alt.Secteur des sciences de la Terre, Contribution externe 20110132
ÉditeurAmerican Geophysical Union
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceRégion extracotière du nord
Lat/Long OENS-100.0000 -90.0000 84.3333 80.0000
Sujetsdonnées sismiques; profils sismiques; levés de refraction sismiques; ondes P; modèles de la croûte; croûte océanique; géologie marine; géophysique
Illustrationslocation maps; seismic profiles; schematic cross-sections; magnetic anomaly maps
ProgrammePreparation of a submission for an extended continental shelf in the Atlantic and Arctic Oceans under UNCLOS, Délimitation du plateau continental du Canada en vertu de la Convention des Nations Unies sur le droit de la mer (UNCLOS)
Diffusé2011 12 03
Résumé(disponible en anglais seulement)
The crustal structure of the Alpha Ridge and its connection to the Canadian Polar Margin was studied by a seismic refraction experiment consisting of a 350-km-long line perpendicular to the margin and of a 175-km-long cross line on the ridge. Explosives with a spacing of 22 km were recorded by geophones deployed on the ice (~1.5 km spacing). P wave velocity models were developed by forward and inverse modeling of travel times and by tomographic inversion. The models show a 30-km-thick continental crust with velocities from 5.5-6.6 km/s. The continent-ocean transition zone is characterized by thinned and intruded continental crust; a high-velocity lower crustal body (7.5 km/s) indicates magmatic underplating. An up to 5-km-thick layer with velocities of 4.7-5.4 km/s can be correlated from the transition zone onto the Alpha Ridge, where reflection seismic data indicate the presence of extrusive volcanics. The transition zone is characteristic for volcanic-style continental margins. The crust on Alpha Ridge consists of the volcanics, a 4-km-thick layer with intermediate velocities of 6.1-6.6 km/s and a lower crustal layer with velocities of 6.8 to 7.3 km/s; Moho depth varies between 26 and 32 km. Velocities on the ridge are similar to other oceanic large igneous provinces. The Alpha Ridge and the contiguous Mendeleev Ridge are interpreted to result from interaction between a Cretaceous plume and a seafloor spreading centre parallel to the Canadian Polar Margin with the Lomonosov Ridge acting as a shear margin.