Preface The expedition ARK XIX/3 with the German icebreaking RV ...

and is probably a reflection of the abundance of life form here (and now largely
destroyed).
The other important discovery that deserves a special mention is the nature of the
numerous scarps that are found along this margin. These have been imaged both on
TOBI side-scan sonar and by the Geological Survey of Ireland multibeam dataset.
These scarps extend for 10s of km and often feature the growth of carbonate mounds.
The coincidence of these scarps with boundary faults and hydrocarbon reservoirs has
lead to the speculation that these may be the sites of cold seeps that have developed
into carbonate mounds. As a result of this cruise we can now dismiss this hypothesis.
The scarps are obviously erosional features with scarp faces revealing consolidated
Quaternary sediments that has then become colonised by suspension feeders. There
was absolutely no evidence of hydrocarbon seepage. Furthermore, where carbonate
mounds grow on this scarp they grow on the tops of the scarps, due to enhanced
hydrodynamics and not from the base up due to a process of feeding by cold seeps.
Although this is a negative conclusion, in many senses this is one of the most
significant finds of the entire cruise.
References
Akhmetzhanov AM, Kenyon NH, Ivanov MK, Wheeler A, Shashkin PV, van Weering TCE
(2003) Giant carbonate mounds and current swept seafloors on the slopes of the southern
Rockall Trough In: Mienert J, Weaver P (eds) European Margin Sediment Dynamics: Sidescan
Sonar and Seismic Images, Springer-Verlag, p.203-210
Croker PF, de Haas H, Huvenne VAI, Wheeler AJ (2003) The 2002 TOBI sidescan survey of
carbonate mounds in the Rockall and Porcupine basins. 46th Annual Irish Geological
Research Meeting, Ulster Museum, Belfast, 21st-23rd February 2003.
Dando PR, Hovland M (1992) Environmental effects of submarine seeping natural gas.
Continental Shelf Research 12: 1197-1207.
Dickson RR, McCave IN (1986) Nepheloid layers on the continental slope west of Porcupine
Bank. Deep-Sea Research 33: 791-818.
de Haas H, Huvenne V, Wheeler A, Unnithan V, shipboard scientific crew (2002) M2002
Cruise report (R.V. Pelagia Cruise 64PE197): A TOBI Side Scan Sonar Survey of Cold
Water Coral Carbonate Mounds in the Rockall Trough and Porcupine Sea Bight - Texel-
Southampton-Galway, 21 June – 14 July 2002. Royal Netherlands of Sea Research,
Texel, The Netherlands, 2002.
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