Influence of bottom current variability on deep-water coral banks: An example from the Belgica mound province, SW of Ireland
Van Rooij, D.; Henriet, J.-P. (2004). Influence of bottom current variability on deep-water coral banks: An example from the Belgica mound province, SW of Ireland, in: 32nd International Geological Congress, Florence, Italy, August 20-28, 2004. Abstract Volume. pp. Abstract 336-8
In: (2004). 32nd International Geological Congress, Florence, Italy, August 20-28, 2004. Abstract Volume. IGC: Florence. 2 vols pp., more
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Document type: Summary
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Coral bank Contourite Seismic stratigraphy Cenozoic |
| Abstract |
Various investigations carried out within the course of the EC FP5 GEOMOUND and ECOMOUND projects highlighted the presence of deep-water coral banks with remarkable faunal habitats on the NE Atlantic slopes off the British Isles. The possible factors controlling the genesis, development and daily sustainment of these mounds are known, but there still is much debate concerning their genesis. The Belgica mound province on the eastern slope of the Porcupine Seabight features large surface mounds in a very complex hydrodynamic environment controlled by tidally influenced enhanced bottom currents. In this paper, we will discuss the role bottom currents have exerted on the genesis and development of the deep-water coral banks since the Neogene.Very high-resolution single channel sparker seismic profiling within this area revealed that the Cenozoic evolution of this area has known several periods of active seabed erosion. A detailed stratigraphic and sediment dynamic study demonstrated that already the position of these mounds was influenced by these erosion events. Since the onset of the present-day ocean circulation system, the sedimentation in this area was influenced by strong bottom currents, as demonstrated by the wide variety of (probably Miocene) buried sediment waves. Within the Pliocene and at the start of the Quaternary, an oceanographic very instable period was responsible for episodic widespread erosion on this margin. This resulted in an early Quaternary seabed with several levels of scarps, ridges and channels. The most elevated features, most of the time located in the vicinity of the buried sediment waves, are now the seat of the coral banks.Moreover, the coral banks are embedded in a probable Quaternary sequence of (several) contourite drifts. The seismic reflection patterns of these drift bodies also suggest most of the mounds already had evolved to an 'adult' phase before the drift sediments were deposited. In this way, the position of the mounds and the already complex early Quaternary seabed morphology formed a suitable place for local current enhancement due to topographic steering, creating small contourite drifts. Core data on these drifts suggest the strength of these bottom currents varied through the Quaternary and could have influenced the growth of the coral banks during glacial episodes. |
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