GEOSCAN, résultats de la recherche


TitreEvidence for an important tectonostratigraphic seismic marker across Canada Basin and southern Alpha Ridge of the Arctic Ocean
AuteurShimeld, J W; Chian, D; Jackson, H R; Hutchinson, D; Mosher, D C; Wade, J A; Chapman, C B
SourceCommission géologique du Canada, Dossier public 6822, 2011, 1 feuille, (Accès ouvert)
Documentdossier public
Mediapapier; en ligne; numérique
Formatspdf; JPEG2000
ProvinceRégion extracotière du nord
Lat/Long OENS-168.0000 -120.0000 80.0000 72.0000
Sujetszones tectonostratigraphiques; antécédents tectoniques; études de la croûte; interpretations sismiques; levés sismiques; levés sismiques marins; profils sismiques marins; levés géophysiques; études de réflexion; levés de reflexion sismiques; milieu sédimentaire; structures sédimentaires; milieux sédimentaires; tectonique; stratigraphie; géologie marine; géophysique
Illustrationsseismic reflection profiles; stratigraphic columns; plots; location 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 09 15
Résumé(disponible en anglais seulement)
An extensive modern dataset of short-offset seismic reflection profiles coupled with wide-angle reflection and refraction sonobuoy records enable new insights into the crustal types, rifting processes, subsidence history, and sedimentary sequences of Canada Basin, Northwind Ridge, and southern Alpha Ridge. Exceeding 6.5 km in thickness across southern Canada Basin and thinning northward to Alpha Ridge, the sedimentary succession is divided into more than a dozen regional seismostratigraphic units, the oldest of which is informally named the bisque unit. Characterized by anomalously high-amplitude reflections, this unit is of interest since it immediately overlies acoustic basement and may indicate something about the nature of basement and its tectonic history. Along southern Alpha Ridge, including Nautilus Spur, the base of the bisque unit is marked by a prominent angular unconformity that can be traced southward into Canada Basin before becoming obscured by deep burial. The bisque unit appears to be concordant with basement topography and it is clearly offset by faults created during the most recent significant extension of the basin. Distinct onlap of overlying units indicates that extension was accompanied by apparently rapid subsidence and then quiescence. Large basement structures interpreted to be volcanic edifices are immediately overlain and at least partially covered by the bisque unit which might indicate a genetic linkage. On sonobuoy records, two distinct phenomena are observed for the bisque layer: 1) wide-angle reflections and refractions on records distributed widely across the study area; and 2) high amplitude phases of anomalously low apparent velocity across northern Canada Basin and Nautilus Spur. The latter are modelled as converted waves with down-going P-to-S and up-going S-to-P conversions occurring at the bisque layer. This is an important phenomenon since it presents the possibility of estimating Poisson's ratio for crustal layers beneath bisque which would be a valuable constraint in determining crustal types. Though not yet sampled, the bisque unit is interpreted to consist of highvelocity siliceous oozes interbedded with hemipelagic and pelagic sedimentation. In Canada Basin, it may correlate with mid-to-upper Cretaceous tuffs of the Christopher and Kanguk formations found on Banks and Prince Patrick islands. The unit may become increasingly younger northward over Alpha Ridge.