The incompleteness of turbidite records: Comparing direct monitoring of turbidity currents to deposits preserved in submarine fans (Pointe-des-Monts, eastern Canada)

Jacques, Florian ORCID: https://orcid.org/0009-0006-3079-3939, Normandeau, Alexandre, Montero-Serrano, Jean-Carlos ORCID: https://orcid.org/0000-0001-7896-6284, St-Onge, Guillaume ORCID: https://orcid.org/0000-0001-6958-4217, Limoges, Audrey, Rochon, André, Neumeier, Urs ORCID: https://orcid.org/0000-0002-4816-3963, Lajeunesse, Patrick et Bourgault, Daniel ORCID: https://orcid.org/0000-0003-0251-4104 (2026). The incompleteness of turbidite records: Comparing direct monitoring of turbidity currents to deposits preserved in submarine fans (Pointe-des-Monts, eastern Canada). Marine Geology, 491 (107660).

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Résumé

The recurrence of turbidity currents in submarine canyons is often assessed using sediment core records from submarine fans, which are generally assumed to reflect canyon processes. However, this assumption has rarely been tested. Here, we assess the completeness of modern sedimentary records in the Pointe-des-Monts submarine fan, located in the Lower St. Lawrence Estuary, eastern Canada, by comparing turbidity current activity derived from repeat multibeam bathymetry, direct monitoring observations, and short sediment cores. The timelapse bathymetry and monitoring results revealed that turbidity current activity over the last 15 years was primarily driven by storms, especially during ice-free winters. Since 2007, a minimum of nine turbidity currents were recorded by timelapse multibeam bathymetry and direct observations in the canyon system, many of which have led to the migration of cyclic steps within the canyon axis. However, turbidites recorded in the short sediment cores on the lobe predate all monitoring efforts, indicating a largely incomplete record of canyon processes preserved on the seafloor. The absence of modern turbidites (≤15 years) in the submarine fan is interpreted to result from bottom current reworking, bioturbation, and the dilution of turbidity currents as they become unconfined on the submarine fan. This study highlights that bottom currents can extensively remobilize turbidites, resulting in a largely incomplete record of turbidity currents on submarine fans. Consequently, caution is needed when reconstructing their recurrence and sediment dynamics using sediment cores, particularly in such dynamic nearshore systems.

Type de document :	Article
Validation par les pairs :	Non
Mots-clés :	Courants de turbidité ; Remobilisation des sédiments par les courants de fond ; Profileur acoustique de courant Doppler ; Bathymétrie multifaisceaux répétée ; Carottes sédimentaires ; Marées cycliques ; Estuaire du Saint-Laurent ; Tempêtes / Turbidity currents ; Bottom current remobilization ; Acoustic Doppler current profiler ; Repeat multibeam bathymetry ; Sediment cores ; Cyclic steps ; St. Lawrence Estuary ; Storms.
Départements et unités départementales :	Institut des sciences de la mer de Rimouski (ISMER)
Date de dépôt :	02 avr. 2026 18:18
Dernière modification :	02 avr. 2026 18:18
URI :	https://semaphore.uqar.ca/id/eprint/3530