Photographic evidence for slope-current activity, Hebrides Slope, NE Atlantic Ocean

Scottish Journal of Geology - Tập 31 Số 2 - Trang 107-115 - 1995
John Howe1, J.D. Humphery2
1British Geological Survey, Marine Geology, Murchison House, West Mains Road, Edinburgh EH9 3LA/Southampton University, Department of Geology, Highfield, Southampton S09 5NH
2Proudman Oceanographic Laboratory, Department of Engineering, Bidston Observatory, Birkenhead, Merseyside, L43 7RA

Tóm tắt

Synopsis Evidence from sea-bed photographs and current-meter data from the Hebrides Slope, indicates that there is a slope-current flowing northward along the bathymetric contours in water depths of 500–1100 m. Structures identified from photographs include: asymmetric linguoid ripples, scours, crag-and-tail structures and current-induced smoothing of the seabed in fine- to medium-grained contourite sands. Bioturbated hemipelagite muds are characterized by populations of the brittle-star Ophiocten. The densities of these decrease with increased current activity, suggesting that the organism is sensitive to stronger flows. Current-meter data reveal peak flows of 15–25 cm s −1 at depths of 1035 m and 457 m, in a north-north-easterly direction, with little depth stratification through the water column, but with fluctuations in velocity and possible tidal oscillation. The current is probably of Eastern North Atlantic Water origin, flowing northwards along the eastern margins of the Rockall Trough.

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