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TitreOrigin and late Quaternary tectonism of a western Canadian continental shelf trough
AuteurMoslow, T F; Luternauer, J L; Rohr, K
SourceContinental Shelf Research vol. 11, no. 8-10, 1991 p. 755-769,
Séries alt.Commission géologique du Canada, Contributions aux publications extérieures 23190
ÉditeurElsevier BV
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceRégion extracotière de l'ouest
SNRC102O; 102P; 103A; 103B
Lat/Long OENS-132.0000 -128.0000 53.5000 51.0000
Sujetsplate-forme continentale; levés sismiques marins; levés sismiques, navire; levés sismiques; fosses abyssales; dépressions; caractéristiques sous-marines; profils sismiques; sedimentation; dépôts glaciaires; relèvement isostatique; coulées de débris; géologie marine; géologie des dépôts meubles/géomorphologie; Tertiaire
Illustrationslocation maps; seismic reflection profiles
ProgrammeFrontier Geoscience Program
ProgrammeCRSNG Conseil de recherches en sciences naturelles et en génie du Canada
ProgrammeUniversity of Alberta Central Research Fund
Résumé(disponible en anglais seulement)
Analyses of high resolution and multi-channel seismic profiles from the central continental shelf of western Canada ascribe a late Quaternary glacial origin to large-scale troughs. Along the margins of Moresby Trough, one of three large-scale cross-shelf bathymetric depressions in Queen Charlotte Sound, seismic profiles within Quaternary sediments show a divergence of reflectors, thickening and folding of seismic units, and concavity of reflectors suggestive of drag. Compactional subsidence, growth faulting, and compaction faulting are also observed. Fault traces commonly terminate below the seabed. Deformation of Quaternary sediments due to faulting is plastic in nature and maximum offset of reflectors is 2.5 m. The observed Quaternary deformation appears to be a product of rapid deposition, loading and subsidence of late Quaternary sediment, which is unrelated to seismic activity. In addition, Quaternary faulting was probably activated by post-glacial loading and isostatic rebound of consolidated Tertiary strata along the margins of continental shelf troughs. The presence of mass movement (slump or debris flow) deposits overlying lithified Tertiary strata along the flanks of Moresby Trough provides the only evidence of seismic activity in the study area. The lack of a mud drape over these deposits implies a late Holocene age for the timing of their emplacement. The Quaternary troughs are incised into Tertiary-aged sedimentary fill of the Queen Charlotte basin. Previous workers had interpreted seafloor escarpments paralleling the trough margins to indicate that the location of Moresby Trough was controlled by renewed or continued activity on Tertiary-aged faults. A multi-channel seismic line across Moresby Trough shows that such an escarpment on the seafloor does not correlate to faults either in the Tertiary basin fill or the underlying basement. Tertiary reflectors are continuous underneath Moresby Trough; the seafloor escarpment is an erosional feature and was not created by reactivation of Tertiary structures. Trough erosion and subsequent fill (up to 175 m thick) are entirely of Quaternary age.