Enigmatic linear furrows and pits on the upper continental slope, northwest Labrador Sea: are they sediment furrows or feeding traces?

• Published in: Atlantic Geology
• Main Authors: Josenhans, Heiner, Lynas, Chris Woodworth
• Format: Article in Journal/Newspaper
• Language: English
• Published: Atlantic Geoscience Society 1988
• Subjects: Hudson; Hudson Strait; Labrador Sea
• Online Access: https://journals.lib.unb.ca/index.php/ag/article/view/1647

Linear furrows and pits were observed from a submersible on the continental slope east of Hudson Strait in water depth ranging from 1004 to 715 m (Fig. 1). The parallel to sub-parallel furrows are typically 15-40cm wide and 20-60 cm deep. These enigmatic features resemble deep-water, current-formed sedimentary furrows but differ in two significant aspects: (1) they consistently have blocky rims (berms) that appear to have been formed by the ploughing action of a rigid object, and (2) they lack any evidence of formation by bottom currents. We describe the local geological setting and compare the furrows with conventional sedimentary furrows. Our observations lead us to propose three tentative mechanisms for furrow formation: (1) formation by dragging of fins or mandibles of deep diving animals such as whales as they forage on the seafloor, (2) current driven ice which is negatively bouyant because of entrapped glacial sediment, or (3) furrowing by current-driven sponge balls which were observed in the troughs of the furrows. RÉSUMÉ Des plongées en submersible sur la pente continentale à l’est du détroit d'Hudson ont révéIé des sillons linéaires et des dépressions par une profondeur de 715 à 1004 m. Ces sillons sont parallèles on presque, typiquement d'une largeur de 15 à 40 cm et d'une profondeur de 20 à 60 cm. Ces structures énigmatiques évoquent les sillons sédimentaires dus a Taction des courants sur les grands fonds mais en différent sur deux points principaux: (1) elles présentent constamment des bordures (replats) morcelées qui semble résulter d'un labourage par un objet rigide et (2) la preuve de leur formation par des courants de fond fait défaut. On décrit le cadre géologique régional et compare ces sillons aux sillons sédimentaires conventionnels. À la ...