Structure, development and sedimentary processes of the upper reaches of the Gollum channel system, SW of Ireland
Van Rooij, D.; Van Landeghem, K.; Huvenne, V. A. I.; Beyer, A.; Henriet, J.-P.; Wheeler, A.; de Haas, H. (2004). Structure, development and sedimentary processes of the upper reaches of the Gollum channel system, SW of Ireland, in: 32nd International Geological Congress, Florence, Italy, August 20-28, 2004. Abstract Volume. pp. Abstract 265-14
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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Canyon Turbidite Seismic stratigraphy Slumps Bottom currents |
| Authors | | Top |
- Van Rooij, D., more
- Van Landeghem, K.
- Huvenne, V. A. I., more
- Beyer, A.
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| Abstract |
The Gollum channel system is the only major downslope sediment supplying system located on the Irish Atlantic margin. However, compared to its counterparts on the Celtic and Armorican margins, its structure and development is yet poorly understood. A variety of new data, collected during several campaigns from 1999 to 2002, has shed a new light on the upper reaches of this system. Multibeam bathymetry, seismic profiling and TOBI side-scan sonar data allow to clearly distinguish two different channel settings. The southern part of the system is characterised by several deeply incised canyons with numerous slide scars on their flanks. Their pathways seem to be influenced by a structural control, creating a bayonet-shaped course. Upstream of this structural feature, the channel floor deposits are characterized by thick acoustically transparent units suggesting ponded turbidites or mass-wasting deposits. A long piston core in such a deposit, however, only yields a small number of fine-grained turbidites in a muddy hemipelagic host sediment. This suggests that this system has known a relatively low activity during Quaternary times. Moreover, at the abyssal end of the slightly sinuous Gollum channel only a weakly developed deep-sea fan is found, confirming a low sediment supply. It was previously thought to be reworked by strong bottom current processes.In the northern part of the system, on the other hand, the Kings channels show an entirely different situation. Here the channels are broad and smooth with relatively gentle flanks. Along the longitudinal axis of the northernmost channel, an intra-channel levee is observed, suggesting a relatively higher activity compared with the more southern Gollum canyons. The most remarkable feature, however, is a large field of mass-wasting deposits and escarpments. This suggests a dramatic phase of slope instability within the Neogene. Until now, little evidence is found for the cause of this event. The evidence of pockmarks north of this area could invoke the mediation of fluid migration.Despite a poor coverage of seismic profiles, the stratigraphy of this area could be linked with the relatively better constrained stratigraphy of the Belgica mound province in the north. This suggests the Gollum channel system was initiated some time during the Miocene. |
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