Carbonate mounds are an important feature along the European North-Atlantic margins. The presence of giant carbonate mounds in the Porcupine Seabight, on the Porcupine Bank, in the Rockall Trough and on the Rockall Bank, west of Ireland, have been known since the nineties and have been the target of several cruises during the last decade. However, the processes of mound build-up and mound nucleation are not yet completely understood. What keeps a mound growing over extended time periods? How does the biosphere interact with sedimentary fluxes to make a mound grow? On which level do palaeoclimatological and palaeoceanographic changes control mound growth? Which diagenetic processes play an important role in carbonate mound generation and how do they affect the mound?

The present study focuses on the nature and significance of the carbonate mound record, and the nature and internal structure of one specific carbonate mound, the Challenger Mound, is described in detail and compared with other mounds from the Irish margin and also with those from the Moroccan margin. The variety of mound characteristics are discussed, along with the associated oceanographic and geological settings and an appropriate classification for recent carbonate mound systems and cold-water coral reefs is presented. Video imagery through Remotely Operated Vehicle (ROV) surveys, provide images of the surface of different carbonate mounds to highlight morphological characteristics of the mounds.

The role of recent carbonate mounds, such as Challenger Mound, in the global carbonate budget is discussed along with inferences on how recent carbonate mounds can be seen as analogues of ancient mud mound systems.