Original Article

Facies

, Volume 54, Issue 1, pp 1-24

Franken Mound: facies and biocoenoses on a newly-discovered “carbonate mound” on the western Rockall Bank, NE Atlantic

  • Claudia WienbergAffiliated withMARUM, Center for Marine Environmental Sciences, University of Bremen Email author 
  • , Lydia BeuckAffiliated withInstitute of Palaeontology, University of Erlangen-Nuremberg
  • , Sebastian HeidkampAffiliated withMARUM, Center for Marine Environmental Sciences, University of Bremen
  • , Dierk HebbelnAffiliated withMARUM, Center for Marine Environmental Sciences, University of Bremen
  • , André FreiwaldAffiliated withInstitute of Palaeontology, University of Erlangen-Nuremberg
  • , Olaf PfannkucheAffiliated withIFM-GEOMAR, Leibniz-Institute of Marine Sciences
  • , Xavier MonteysAffiliated withGeological Survey of Ireland, Beggars Bush

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Abstract

Cold-water coral carbonate mounds are widespread along the Irish continental margin. Whereas the Porcupine Seabight and the Rockall Trough are relatively well studied with regard to mound topography, coral coverage, and benthic life diversity, the situation on the western Rockall Bank is rather unknown. Detailed facies and biocoenoses mapping based on video footage analyses was conducted on the newly-discovered Franken Mound. Facies were identified ranging between cliff-like to planar hardgrounds and soft sediments that are partly rippled. A variety of biocoenoses are associated with these facies comprising discrete live coral colonies, dense live and dead coral framework coverage, abundant to scattered coral debris, and a soft sediment faunal community, whereas the latter is three times less speciose as biocoenoses containing live framework-building corals. The facies and biocoenosis classes are supplemented by exposed dropstones, lost fishery nets, and rubbish. The distribution of the classes clearly indicates a close relationship with local current effects and current intensification. Due to the dominance of dead coral framework and the partially exposed internal sediment sequences on the mound flanks, it is assumed that Franken Mound is approaching the “mound retirement” mound growth state.

Keywords

Facies Biocoenoses Cold-water corals Carbonate mound Current regime Franken Mound Western Rockall Bank