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TitreTide-supported gravity flows on the upper delta front, Fraser River delta, Canada
AuteurAyranci, K; Lintern, D G; Hill, P R; Dashtgard, S
SourceMarine Geology vol. 326-328, 2012 p. 166-170, https://doi.org/10.1016/j.margeo.2012.09.007
Année2012
Séries alt.Secteur des sciences de la Terre, Contribution externe 20120230
ÉditeurElsevier
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1016/j.margeo.2012.09.007
Mediapapier; en ligne; numérique
Formatspdf
ProvinceColombie-Britannique
SNRC92G/03
Lat/Long OENS-123.5000 -123.0000 49.2500 49.0000
Sujetsmarées; courants de marée; deltas de marée; dépôts de marée; milieux de marée; turbidites; structures flui dales; mécanismes d'écoulement; regimes d'écoulement; glissement par gravité; gravité; géologie marine
Illustrationslocation maps; graphs; plots
ProgrammeRisques géo marines, Géoscience pour la sécurité publique
Résumé(disponible en anglais seulement)
Three anomalous events (AEs) were recorded off the Fraser River, Canada during the freshet of 2008, and are ascribed to quasi-continuous gravity flows. These flows transport warm, low-salinity Fraser River waters to the upper delta front of the Fraser delta to at least 50 m water depth. All flows occurred during the freshet and spring ebbing tide, and were characterized by deposition of fine-grained sand and silt beds with likely high-water contents. These sediments were susceptible to resuspension by the subsequent flood-tide current, producing very high near bed suspended sediment concentrations (SSC) with enough excess density to generate hyper-concentrated flows. Our observations show that these episodic events result from the combination of high river discharge, high SSC, and strong tides, and therefore, are likely to occur on the delta fronts of other large tide-dominated and tide-influenced rivers. In shallow-water basins (< 50 m water depth), these tide-supported gravity flows can affect sediment deposition on both the delta front and prodelta.
GEOSCAN ID291912