--> --> Abstract: Neogene Sedimentary Processes of Submarine Channels, West Off Ireland, by David Van Rooij, Katrien Van Landeghem, Charlotte Skonieczny, Jeroen Ingels, Sébastien Zaragosi, Veerle Huvenne, Andrew J. Wheeler, Henk de Haas, and Jean-Pierre Henriet; #90082 (2008)

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Neogene Sedimentary Processes of Submarine Channels, West Off Ireland

David Van Rooij1, Katrien Van Landeghem2, Charlotte Skonieczny3, Jeroen Ingels4, Sébastien Zaragosi3, Veerle Huvenne5, Andrew J. Wheeler2, Henk de Haas6, and Jean-Pierre Henriet1
1Renard Centre of Marine Geology, Ghent University, Gent, Belgium
2Department of Geology, University College Cork, Cork, Ireland
3Departement de Geologie et Oceanographie, Université Bordeaux I, Bordeaux, France
4Marine Biology Section, Ghent University, Gent, Belgium
5Geology and Geophysics Group, National Oceanography Centre, Southampton, United Kingdom
6Royal NIOZ, Texel, Netherlands

The Gollum Channel System is the only major downslope sediment supplying system on the Irish Atlantic margin. A decade ago, its structure and development was still poorly understood, compared with its counterparts on the Celtic and Armorican margins. A variety of data, collected from 1999 to 2006, has shed a new light on the upper reaches of this system. These data allowed to clearly distinguish two different channel settings. The main Gollum channel 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, however, only yields a small number of fine-grained turbidites in a muddy hemipelagic host sediment. This implies 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. 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 bottom current activity compared with the southern Gollum channels. The most remarkable feature, however, is a large field of mass-wasting deposits and escarpments. This calls for 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.

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