GEOSCAN, résultats de la recherche


TitreTurbidite deposition: the role of initiating process and slope morphology on mid-latitude continental margins
AuteurPiper, D J; Normark, W R
SourceAAPG 2008 annual convention and exhibition, abstracts volume; 2008 p. 160-161
Séries alt.Secteur des sciences de la Terre, Contribution externe 20070451
ÉditeurAmerican Association of Petroleum Geologists
RéunionAmerican Association of Petroleum Geologists Annual Convention; San Antonio; US; avril 20-23, 2008
ProvinceRégion extracotière de l'est
Sujetstalus continental; marges continentales; roches sédimentaires; turbidites; paléogéographie; érosion; milieu sédimentaire; distribution des sédiments; transport des sediments; sédiments marins; sédimentologie; géologie marine; Cénozoïque; Quaternaire
ProgrammeLes géosciences à l'appui de la gestion des océans, Aléas géologiques et contraintes à la mise en valeur des ressources extracôtières
Résumé(disponible en anglais seulement)
The initiation mechanisms for late Quaternary turbidites on the eastern Canadian and western U. S. margins are compared to evaluate which processes are common to both passive and active margins and which are not. Numerous local studies in both regions have inferred initiation mechanisms for turbidity currents, based on sparse real-time data for historical flows, and inferences based on the age and contemporary paleogeography, erosional features, and depositional record of well-studied flows. In both areas, three major types of initiation process are recognised: transformation of failed sediment, hyperpycnal flow from rivers or ice margins, and resuspension of outer shelf sediment by oceanographic processes. Most high-concentration flows result from hyperpyncal supply of hyperconcentrated bedload, or liquefaction failure of coarse-grained sediment, and tend to deposit in slope conduits and gradients < 0.4° at the base of slope and on mid-fan areas. Highly turbulent flows from transformation of prolonged retrogressive failures and from ignitive flows triggered by oceanographic processes tend to cannibalize these more proximal sediments and deposit on gradients of < 0.2° on basin plains. Most sediment failures do not result in large turbidite beds.
Initiation mechanism exerts a strong control on the duration of turbidity-current flows. In most basins, there is a complex feedback between different types of turbidity-current initiation and the associated slope morphology. It is therefore unlikely that there is a simple relationship between the type of turbidite bed (e.g. a classical Bouma-sequence turbidite) and an initiating process (e.g. sediment failure).