GEOSCAN, résultats de la recherche


TitreCrustal structure of the central Nova Scotia margin off eastern Canada
AuteurWu, Y; Louden, K E; Funck, T; Jackson, H R; Dehler, S A
SourceGeophysical Journal International vol. 166, 2006 p. 878-906, (Accès ouvert)
Séries alt.Commission géologique du Canada, Contributions aux publications extérieures 2005124
ÉditeurOxford University Press (OUP)
Documentpublication en série
Mediapapier; en ligne; numérique
Formatspdf (Adobe Acrobat Reader)
ProvinceNouvelle-Écosse; Région extracotière
SNRC11C; 11D; 10N; 10O
Lat/Long OENS -64.0000 -60.0000 45.0000 40.0000
Sujetsstructure de la croûte; marges continentales; levés de refraction sismiques; études de réfraction; volcanisme; levés de reflexion sismiques; études de réflexion; séismologie; serpentinisation; formation de failles; géologie structurale; tectonique; géophysique
Illustrationslocation maps; seismic profiles; cross-sections, structural; graphs
ProgrammeConsolidation du savoir géoscientifique du Canada
ProgrammeCRSNG Conseil de recherches en sciences naturelles et en génie du Canada
Résumé(disponible en anglais seulement)
The central Nova Scotia margin off Eastern Canada is located at a transition from a volcanic margin in the south to a non-volcanic margin in the north. In order to study this transition, a wide-angle refraction seismic line with dense airgun shots was acquired across the central Nova Scotia margin. The 500-km-long transect is coincident with previous deep reflection profiles across the Lahave Platform and extending into the Sohm Abyssal Plain. A P-wave velocity model was developed from forward and inverse modelling of the wide-angle data from 21 ocean bottom seismometers and coincident normal-incidence reflection profiles. The velocity model shows that the continental crust is divided into three layers with velocities of 5.5-6.9 km s-1. The maximum thickness is 36 km. A minor amount (-5 km) of thinning occurs beneath the outer shelf, while the major thinning to a thickness of 8 km occurs over the slope region. The seaward limit of the continental crust consists of 5-km-thick highly faulted basement. There is no evidence for magmatic underplating beneath the continental crust. On the contrary, a 4-km-thick layer of partially serpentinized mantle (7.6-7.95 km s-1) begins beneath the highly faulted continental crust, and extends ?200 km seawards, forming the lower part of the ocean-continent transition zone. The upper part of the transition zone consists of the highly faulted continental crust and 4- to 5-km-thick initial oceanic crust. The continent-ocean boundary is moved ?50 km farther seawards compared to an earlier interpretation based only on reflection seismic data. The oceanic crust in the transition zone consists of layer 2 and a high-velocity lower crustal layer. Layer 2 is 1-3 km thick with velocities of 5.6-6.0 km s-1. The high-velocity lower crustal layer is 1-2 km thick with velocities of 7.25-7.4 km s-1, suggesting a composite layer of serpentinized peridotite and gabbroic layer 3. Oceanic crust with normal thickness of 5-7 km and more typical layer 3 with velocities of 6.95-7.3 km s?1 is observed at the seaward end of the profile.