Surficial geology and glaciomarine geomorphology of Baffin Bay continental shelf sites based on ROV observations, multibeam bathymetry, and acoustic sub-bottom profiles

English Abstract:

The continental margins of Baffin Bay were strongly influenced by Quaternary glaciations, which left behind glaciomarine geomorphic features at continental slope depths. We surveyed surficial geology and associated geomorphology of three glacially-influenced environments on the margins of Baffin Bay using a Remote Operated Vehicle (ROV) as part of a broader program on deep-sea corals and sponges. ROV dive locations were guided by multibeam bathymetry, sub-bottom profiles, and fisheries bycatch data. An ROV dive on the Disko trough-mouth fan in 900 m depth in SE Baffin Bay found dominantly mud, at low slopes, with rare exposures of angular cobbles and boulders. Fan lobes were indistinct but recognizable in contour-parallel sub-bottom profiles, but were not readily apparent in multibeam bathymetry. On rill-and-gully morphology of the Home Bay trough-mouth fan at about 750 m depth in SW Baffin Bay, identified from multibeam bathymetry, sand and mud bottoms dominated, with commonly occurring highly angular cobble and boulders. Steeper slopes often, but not always, had greater exposure of cobbles and boulders. A bedrock massif within the Scott Inlet trough at ~600 m depth in W Baffin Bay had exposed bedrock only on the vertical cliff face. This vertical cliff may have been linked to faulting. Atop the massif, bedrock was usually covered by a veneer of sediment, including sand, gravel, and angular cobbles and boulders, but this veneer was not detected in sub-bottom profile. The sediments atop of the massif are probably derived from ice-rafted debris. Glacial megaflutes in sediments were observed in multibeam bathymetry downdrift from another massif within the trough. Hydrocarbon release associated with previously described hydrocarbon seeps at the Scott Inlet site was observed as an oil slick at the sea surface, but no direct evidence of hydrocarbon-related authigenic carbonates was observed during the ROV dive. Although subfossil calcareous deep-sea corals have been collected from the Labrador Sea and SE Baffin Bay, none were observed in western Baffin Bay. The modern benthic faunal composition differed greatly among sites, with greatest differences observed between Eastern and Western Baffin Bay. Faunal composition is probably affected by bottom currents and water mass characteristics, as well as geomorphology.