Cold Water Coral Mounds in the Eastern Alboran Sea: Geomorphology and Environmental Context

Claudio Lo Iacono, Eulalia Gràcia, César R. Ranero, Rafael Bartolome, and Cruise Party MeLCOR

Cold Water Coral (CWC) mounds are prominent features in the Eastern Alboran Sea and have been mapped both in the northern Spanish Margin and in the southern Moroccan margin. Based on the integration of highresolution geophysical methods, seafloor sampling and video images, we present the main morphological characters of the mounds and their associated benthic habitats. CWC mounds have been observed as isolated ridges on seamounts (e.g. Chella Bank in the Spanish margin) and as large clusters of circular and elongated mounds (e.g. Cabliers Mound and Melilla Mound Field) in the Moroccan margin. Mounds display a relevant variety in their dimensions. They range in 40-400 m large, 5-70 m high from the surrounding seafloor and a high density has been observed in some of the clusters of the Moroccan Margin (up to 5 mounds per km²). Parametric echo-sounder, highresolution sparker and deep seismic data reveal that mounds built above volcanic or structurally controlled hard substrate or either on mass movement deposits. Video tracks and seafloor sampling showed the occurrence of CWC frameworks composed of dead and patchily live Madrepora oculata, Lophelia pertusa and Dendrophilia cornigera in a fine to medium coarse bioclastic sediments matrix. Most common associated macrobenthic communities correspond to gorgonian assemblages (Callogorgia verticillata, Paramuricea sp.) and echinoderms (Ophiotrix sp.). Along the Moroccan margin, some older mounds appear to be buried, suggesting a polyphasic evolution of mound clusters, probably related to glacioeustatic oscillations during the upper Pleistocene-Holocene. A first approach has been attempted in order to describe the interplay between the regional physical characters and the evolution of the CWC mounds in the Eastern Alboran Sea, probably affected by the hydrodynamic regime and the strong productivity of the area, the peculiar sedimentary environments and the on-going tectonic activity in the Southern Margin.

AAPG Search and Discovery Article #90161©2013 AAPG European Regional Conference, Barcelona, Spain, 8-10 April 2013