| Titre | Sediment redistribution processes in Baffin Island fjords |
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| Auteur | Syvitski, J; Normandeau, A |
| Source | Marine Geology vol. 458, 107024, 2023 p. 1-21, https://doi.org/10.1016/j.margeo.2023.107024  Accès ouvert |
| Image |  |
| Année | 2023 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20220367 |
| Éditeur | Elsevier |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1016/j.margeo.2023.107024 |
| Media | papier; numérique; en ligne |
| Formats | pdf; html |
| Province | Nunavut |
| SNRC | 16; 17; 18; 26; 27; 28; 36; 37; 38 |
| Région | île de Baffin |
| Lat/Long OENS | -75.6667 -60.0000 72.1667 64.5000 |
| Sujets | sédimentologie; Sciences et technologie; Nature et environnement |
| Illustrations | cartes de localisation; tableaux; imagerie satellitaire; diagrammes; diagrammes; photographies; images sismiques |
| Programme | Géoscience pour la sécurité publique Baie de Baffin |
| Diffusé | 2023 03 07 |
| Résumé | (disponible en anglais seulement)
Four decades of studies on pristine Baffin Island fjords are summarized with respect to sediment redistribution processes and resulting deposits. Sediment fill
in these fjords occurred during the Holocene epoch, when deglacial and postglacial processes led to a sandy-mud fill of basins. The sand component mostly enters the fjord basins from chute failures along the shorelines of deltas, triggering the
release of yearly turbidity currents. These currents can travel long distances, often within leveed channels, leaving behind a seafloor of migrating cyclic steps that eventually transform into sediment waves. Channelized cyclic steps migrate at tens
of meter per year whereas finer-grained sediment waves, mostly unconfined,migrate at much lower rates. Moored instruments and sediment traps in two fjords show that turbidity currents occur mostly between May and mid-August, when meltwater supply
from glaciers is at its maximum. Not surprisingly, moored instruments were dragged downslope by turbidity current impact, suggesting high-concentration of suspended sediment within a thin near-bed layer. In rarer cases, large debris flows form even
larger and longer submarine channels that carry sediment for 10s of kilometersinto the deep basin. These slide-generated debris flows can reorganize the basin floor as a sediment conduit for follow-on turbidity currents across thousands of years.
Whereas sand is transferred to the deeper basin by turbidity currents, mud accumulates on the steep sidewall slopes and in the deep basin. Where mud accumulates on steep (=13º) margins, many sidewall failures occur. Notably, the right-hand margins
contain a thicker sediment package and are affected by more sidewall failures than the left-hand side, primarily due to the Coriolis effect on increasing sediment accumulation rates. Of the many sidewall slope failures documented in Baffin Island
fiords, iceberg collision with the seafloor is the only triggering mechanism directly observed. The association between subaerial debris flow fans and margin failures indicates that rock avalanches and subaerial debris flows also play a key role in
triggering sidewall failures. The active seismic zone along Baffin Bay, likely initiated rare but large deep-seated landslides observed in the sedimentary record. This review of four decades of research, reveals Baffin fjords as incredibly dynamic
coastal environments with an ability to annually redistribute large masses of submarine sediment. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Un examen des processus de redistribution des sédiments dans les fjords de l'île de Baffin basé sur des données recueillies entre 1980 et
2020 |
| GEOSCAN ID | 330931 |
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