Abstract
Measurements of near-seabed currents at different carbonate mound locations have demonstrated the presence and influence of bottom-magnified diurnal-period tidal motions. These bottom-trapped waves occur at a depth where the product of local vertical density stratification and seabed slope is a maximum. The seabed currents are magnified significantly if the diurnal forcing period is resonant with the combination of stratification and seabed slope. At the Belgica mounds (eastern Porcupine Sea Bight), there is a correlation between the cross-slope alignment of individual carbonate mounds and the direction of the major axis of the largest (diurnal) tides. The pattern suggests that the enhanced tidal currents play a major role in the shape of developing mounds over a long time period. A similar relation appears to hold at the Logachev mounds (SE Rockall Bank), although less clear because tides are not amplified to the same degree. At other mound locations where enhanced diurnal currents are not present, a more irregular distribution is observed. This suggests that the diurnal currents may be important only at certain carbonate mound locations, and that at these locations a more distinctive alignment of mound structures is produced.
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Acknowledgements
This work was supported through field measurements made during the European Commission funded programs Ecomound (EC contract no. EVK3-CT1999-00013) and ACES (EC contract no. EVK3-CT1999-00008), together with support from the Irish Marine Institute and through the HERMES project, EC contract no. GOCE-CT-2005-511234, funded by the EC’s Sixth Framework Programme under the priority ‘Sustainable Development, Global Change and Ecosystems.’ Bathymetry data were kindly provided by the Geological Survey of Ireland through the Irish National Seabed Survey.
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White, M., Roberts, J.M. & van Weering, T. Do bottom-intensified diurnal tidal currents shape the alignment of carbonate mounds in the NE Atlantic?. Geo-Mar Lett 27, 391–397 (2007). https://doi.org/10.1007/s00367-007-0060-8
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DOI: https://doi.org/10.1007/s00367-007-0060-8