Morphology and sedimentology of (clustered) cold-water coral mounds at the south Rockall Trough margins,NE Atlantic Ocean |
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Authors: | Henk de Haas Furu Mienis Norbert Frank Thomas O Richter Reinhold Steinacher Henko de Stigter Cees van der Land Tjeerd C E van Weering |
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Institution: | (1) Royal Netherlands Institute for Sea Research, P.O. Box 59, AB, 1790 Den Burg, The Netherlands;(2) Department of Paleoclimatology and Geomorphology, VU University Amsterdam, De Boelelaan 1085, HV, 1081 Amsterdam, The Netherlands;(3) Laboratoire des Sciences du Climat et de l’Environnement (LSCE), CNRS, Bat. 12, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France;(4) Present address: Ampfererstr. 34, 6020 Innsbruck, Austria |
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Abstract: | Cold-water coral mounds on both margins of the Rockall Trough (NE Atlantic Ocean) have a strongly different morphology. Single,
isolated mounds occur on the SE margin and are mainly found on the upper slope between 900 and 650 m water depth, while large
mound clusters are found on the SW margin in water depths between 600 and 1,000 m, in a narrow zone almost parallel to the
slope. Sedimentation rates on the mounds are higher than on the surrounding seabed as a result of baffling of biogenic carbonate
debris and siliciclastic particles by the coral framework covering the mounds. This is confirmed by 210Pb measurements. The individual coral growth rate can be three times higher then the vertical growth rate of the coral cover
(±10 mm year−1) which in turn is more than an order of magnitude higher then the present-day overall mound growth rate (±0.25 mm year−1). The presence of extensive hardgrounds and firmgrounds and the three-dimensional coral framework are considered to be responsible
for the stability of the relatively steep slopes of the mounds. High current velocities in the intramound areas result in
local non-sedimentation and erosion, as is shown by the presence of IRD (ice-rafted debris) lag deposits on the seabed and
moats around some of the mounds. The morphology and sedimentology of cold-water coral-covered (mainly Lophelia pertusa and Madrepora oculata) mounds on the southern Rockall Trough margins (NE Atlantic Ocean) is discussed and a model describing the development of
these mounds is presented. |
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Keywords: | Cold-water coral mounds Cold-water corals NE Atlantic Ocean Rockall Trough Margin Model |
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