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TitreDynamics of sediments on a glacially influenced, sediment starved, current-swept continental margin: the SE Grand Banks Slope off Newfoundland
AuteurRashid, H; Piper, D J W; MacKillop, K; Ouellette, D; Vermooten, M; Muñoz, A; Jiménez, P
SourceMarine Geology vol. 408, 2018 p. 67-86,
Séries alt.Ressources naturelles Canada, Contribution externe 20180295
ÉditeurElsevier BV
Documentpublication en série
Mediapapier; en ligne; numérique
Formatspdf; html
ProvinceRégion extracotière de l'est; Terre-Neuve-et-Labrador
Lat/Long OENS -48.5833 -46.1667 46.5000 45.2500
Sujetsmarges continentales; talus continental; sédiments marins; contourites; boues; courants; dépôts de glissement de terrain; dépôts de coulée de débris; dépôts glaciaires; tills; glissements de terrain; coulées de débris; glissements de pentes; etudes isotopiques; isotopes d'oxygène; méthodes de fluorescence aux rayons x; géochimie des sédiments marins; carottes de sédiment marin; levés géophysiques; levés acoustiques marins; sonar latéral; bathymétrie; levés sismiques marins; levés de reflexion sismiques; profils sismiques; antécédents géologiques; antecedents glaciaires; antecedents de sedimentation; sedimentation; analyses stratigraphiques; corrélations stratigraphiques; transport des sediments; distribution des sédiments; régions émettrices; escarpements; escarpements; rigoles; chenaux; analyses de la stabilité des pentes; limites d'atterberg; analyse de limites de plasticité; analyse de limite de liquidité; secousses séismiques; analyses de faciès; modèles; Calotte glaciaire Laurentide; sédiments glaciomarins; courants glaciaires; géologie marine; géologie des dépôts meubles/géomorphologie; géophysique; géochimie; géologie de l'ingénieur; minéralogie; stratigraphie; Phanérozoïque; Cénozoïque; Quaternaire
Illustrationslocation maps; geoscientific sketch maps; tables; seismic profiles; profiles; lithologic sections; geophysical logs; plots; correlation sections; models; cartoons
ProgrammeGéo-risques marins, Géoscience pour la sécurité publique
Diffusé2018 11 22
Résumé(disponible en anglais seulement)
The SE Grand Banks Slope is unusual on the glaciated eastern Canadian margin in that it was remote from ice stream and glacial ice of the Laurentide Ice Sheet (LIS). It thus allows an analysis of the role of contour currents and landslides in sculpting the continental margin, processes that are largely masked where downslope proglacial sediment supply dominated. Detailed oxygen isotope, geotechnical, pXRF, and bulk sediment geochemical analyses were made on seven piston cores and were placed in context using multi-beam bathymetry and high-resolution seismic reflection profiles. Cores have a record of sedimentation back to MIS6 preserved in autochthonous sediment and slide blocks, contourites and mass-transport deposits (MTDs). Detrital?carbonate-rich Heinrich layers (H) are present throughout the succession, but red mud layers of glacial meltwater origin from ice-streams in the SE sector of the LIS are identified only during MIS2 and late MIS3. Both layers allowed high-resolution correlation between cores. Sediments on the upper slope above H2 are condensed and the section above H1 is<50 cm thick, indicating that the powerful Labrador Current winnowed the section above H2. In contrast to the upper slope, approximately 3 to 5m sediments were recorded in the mid-slope above H2 suggesting that the Labrador Current was weaker. Regional stratigraphic variations compared to Flemish Pass and Orphan Basin to the north suggest that NE Newfoundland sources of sediment played an important role and may have been previously underestimated. This study demonstrates that across-margin thickness variations reflect the character and distribution of the Labrador Current sediment transport system through time.
Five horizons with MTDs with headscarps generally up to 25m high are recognized in the upper 50-70 m. Thick MTDs are blocky in cores and in their seismic and bathymetric expression resemble spreads, with local thin mud clast conglomerates that ran out as debris flows over the contemporaneous seabed. Geotechnical data suggest that the seabed is stable under static conditions, although there is geological evidence for fluid escape and geotechnical evidence for under-consolidation. Weak layers along which failure took place are found somewhere around H3-H4 and at or near the top of H5 and MIS6. The low plasticity and liquid limit of the H layers make these layers susceptible to failure during cyclic loading. Episodic earthquakes are the most likely cause of failure.
Résumé(Résumé en langage clair et simple, non publié et disponible en anglais seulement)
Defines the style, age and weak layers of submarine landslides in the Salar Basin, SE Grand Banks Slope.