| Titre | Sediment density flow distribution on wave-influenced deltas |
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| Auteur | Normandeau, A ;
Eamer, J; Bernatchez, P; Didier, D; Lajeunesse, P; Montero-Serrano, J C; Limoges, A |
| Source | Sedimentology 2022 p. 1-42, https://doi.org/10.1111/sed.13033 |
| Image |  |
| Année | 2022 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20220037 |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1111/sed.13033 |
| Media | papier; numérique; en ligne |
| Formats | pdf |
| Sujets | deltas; courants de turbidite; Estuaire du Saint Laurent; Sciences et technologie; Nature et environnement; sédimentologie |
| Illustrations | diagrammes; tableaux; photographies; imagerie satellitaire |
| Programme | Géosciences marines pour la planification spatiale marine |
| Diffusé | 2022 08 19 |
| Résumé | (disponible en anglais seulement)
Deltas are at the transition between fluvial and marine sedimentary environments where sediment density flows are often triggered during high river discharge
events, forming submarine channels and sediment waves. On wave-influenced deltas, longshore currents are particularly efficient at transporting sediment alongshore, reducing the likelihood of sediment density flows from occurring at river mouths.
This study describes four deltaic sedimentary systems at different stages of their evolution on a formerly glaciated continental inner shelf of eastern Canada in order to better understand the distribution of sediment density flows on wave-influenced
deltas. Three types of settings are recognized as being prone to sediment density flows: (i) in the early stages of wave-influence and on large deltas, converging longshore currents can lead to offshelf sediment transport; (ii) on wave-influenced to
wave-dominated deltas, a sandy spit can re-route the river mouth and sediment density flows form where the spit intersects the delta lip; (iii) in advanced stages of wave-dominated deltas and during their demise, rocky headlands are exposed and can
intersect the slope, where off-shelf sediment transport occurs. These types of sediment density flows were all characterized by debris flows or surge-type turbidity currents which have limited offshore run-out. More rarely, hyperpycnal flows form at
the river mouths, especially where the river incises glaciomarine clays prone to landsliding in the river, which increases fine-grained fluvial suspended sediment concentration. Overall, these results highlight the predominance of fluvial-dominated
deltas during a phase of relative sea-level fall combined with high sediment supply. However, as soon as sediment supply diminishes, wave action remobilizes sediment alongshore modifying the distribution and types of sediment density flows occurring
on wave-influenced deltas. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Cette étude examine la distribution des avalanches sous-marines sur des deltas fortement influencés par les vagues. |
| GEOSCAN ID | 329990 |
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