Updated surficial geology compilation of the Scotian Shelf Bioregion, offshore Nova Scotia and New Brunswick, Canada

Philibert, G; Todd, B J; Campbell, D C; King, E L; Normandeau, Alexandre; Hayward, S E; Patton, Emma; Campbell, Lucy

doi:10.4095/330474

Cited by 2 publications

(4 citation statements)

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“…In addition, there are no significant erosive bases (although minor scouring is observed) or massive sediment beds typical of basal turbidites, suggesting a process other than turbidity currents for the laminated facies. Furthermore, muddy sand within Scotian Slope canyon heads is limited to water depths <1000 m (Piper & Campbell, 2002;Mosher et al, 2004), which Li et al (2019) attributed to the presence of internal tides.…”

Section: Origin Of Muddy Sand In Logan Canyon Headmentioning

confidence: 99%

“…Rather, the Logan Canyon mud aggregates are likely the product of clay flocculation facilitated by the presence of organic polymers (i.e. bioflocculation) where concentrations of organic matter are elevated (Pejrup, 2003) and/or grain collision under turbulent conditions (Winterwerp, 1998) resulting in loosely packed aggregates. In particular, sufficiently high SSC and moderate turbulence promotes aggregation in submarine canyon settings (Haalboom et al, 2021).…”

Section: Origin Of Muddy Sand In Logan Canyon Headmentioning

confidence: 99%

“…Sable Island Bank, on the shelf surrounding Logan Canyon, consists primarily of transgressive sands whereas the upper slope is dominated by muddy sand (Hill & Bowen, 1983; Philibert et al ., 2022). The mean tidal range at the head of Logan Canyon is about 1 m and tidal currents on the shelf produce bottom velocities of about 0.3 to 0.4 m/s (Mobil Oil Canada Ltd, 1983; Li et al ., 1997).…”

Section: Regional Settingmentioning

confidence: 99%

“…Therefore, most submarine canyons on high‐latitude passive margins are considered inactive and are currently filling with sediment (e.g. Normandeau & Campbell, 2021; Gao et al ., 2022). The inactivity of such high‐latitude passive margins is exemplified by Scotian Slope submarine canyons which were cut off from glaciofluvial sediment input at ca 13 cal ka bp and experienced sea‐level rise that disconnected canyon heads from the coast by 300 km (Skene & Piper, 2006; Normandeau & Campbell, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Sedimentary record of bottom currents and internal tides in a modern highstand submarine canyon head

Normandeau,

Dafoe,

et al. 2023

Sedimentology

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The evolution of submarine canyons is primarily controlled by turbidity currents, which erode and fill them over time; however, many other hydrodynamic currents operate within canyons. Bottom currents from these other hydrodynamic processes, including internal tides, can be dominant processes, but their deposits are seldom recognized in sediment cores or the rock record. This study combines autonomous underwater vehicle swath bathymetry imagery and sub‐bottom profiles, high‐resolution sediment core analyses (X‐ray imagery and thin sections), and previously collected seabed video and flow measurements within Logan Canyon head (eastern Canada) to provide a detailed, modern record of facies associated with hydrodynamic processes in a canyon head. These results suggest that bottom currents are responsible for maintaining gullies on canyon sidewalls and an axial channel on the canyon floor. Thin sections of sediment cores reveal that muddy sand in the canyon head consists of mud aggregates and silt and fine‐grained sand, both behaving similarly in terms of flow dynamics. Three facies are present at macro‐scale and micro‐scale: laminated, partially laminated and bioturbated sandy mud. Sedimentary structures include rhythmic sand and mud aggregate couplets, planar to wavy laminations, current ripple cross‐laminations and fining‐upward successions, which are attributed to bottom currents induced by internal tides. Bioturbated facies, characterized by discrete biogenic structures and cross‐cutting relationships, predominate and overprint a mottled background. A mottled bioturbation fabric also alternates with or locally disrupts layering within the partially laminated facies. Internal tide currents, capable of bedload transport and forming ripples, were measured during a monitoring period in the canyon head, followed by rapid re‐establishment of benthos and associated biogenic structures, supporting the core interpretations. Preservation of sedimentary facies associated with these internal tides occurs when the sedimentation rate outpaces the rate of bioturbation, likely during stormier conditions on the shelf. These results represent observations of sedimentary facies associated with modern bottom currents and internal tides, and can be used to interpret similar occurrences within the rock record.

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Section: Origin Of Muddy Sand In Logan Canyon Headmentioning

confidence: 99%

Section: Origin Of Muddy Sand In Logan Canyon Headmentioning

confidence: 99%

Section: Regional Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sedimentary record of bottom currents and internal tides in a modern highstand submarine canyon head

Normandeau,

Dafoe,

et al. 2023

Sedimentology

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Predictive mapping of organic carbon stocks in surficial sediments of the Canadian continental margin

Epstein,

Fuller,

Hingmire

et al. 2024

Earth Syst. Sci. Data

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Abstract. Quantification and mapping of surficial seabed sediment organic carbon have wide-scale relevance for marine ecology, geology and environmental resource management, with carbon densities and accumulation rates being a major indicator of geological history, ecological function and ecosystem service provisioning, including the potential to contribute to nature-based climate change mitigation. While global analyses can appear to provide a definitive understanding of the spatial distribution of sediment carbon, regional maps may be constructed at finer resolutions and can utilise targeted data syntheses and refined spatial data products and therefore have the potential to improve these estimates. Here, we report a national systematic review of data on organic carbon content in seabed sediments across Canada and combine this with a synthesis and unification of the best available data on sediment composition, seafloor morphology, hydrology, chemistry and geographic settings within a machine learning mapping framework. Predictive quantitative maps of mud content, dry bulk density, organic carbon content and organic carbon density were produced along with cell-specific estimates of their uncertainty at 200 m resolution across 4 489 235 km2 of the Canadian continental margin (92.6 % of the seafloor area above 2500 m) (https://doi.org/10.5683/SP3/ICHVVA, Epstein et al., 2024). Fine-scale variation in carbon stocks was identified across the Canadian continental margin, particularly in the Pacific Ocean and Atlantic Ocean regions. Overall, we estimate the standing stock of organic carbon in the top 30 cm of surficial seabed sediments across the Canadian shelf and slope to be 10.9 Gt (7.0–16.0 Gt). Increased empirical sediment data collection and higher precision in spatial environmental data layers could significantly reduce uncertainty and increase accuracy in these products over time.

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Updated surficial geology compilation of the Scotian Shelf Bioregion, offshore Nova Scotia and New Brunswick, Canada

Cited by 2 publications

References 0 publications

Sedimentary record of bottom currents and internal tides in a modern highstand submarine canyon head

Sedimentary record of bottom currents and internal tides in a modern highstand submarine canyon head

Predictive mapping of organic carbon stocks in surficial sediments of the Canadian continental margin

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