For the first time, sedimentary sequences through a giant carbonate mound and adjacent off-mound areas were drilled on IODP Exp. 307 -Modern Carbonate Mounds: Porcupine Drilling-. Preliminary results show that the mound evolution is enhanced by the presence of sediment-trapping cold-water corals from the beginning of mound growth in the Early Pleistocene. Indications for hydrocarbon seepage on mound evolution are weak so far. This proposal intends to investigate coral mound evolution as a mirror of biological, sedimentological and palaeoceanographic interactions during the past 2 Ma years based on on-mound and off-mound IODP core sections. For comparison, the excellently preserved La Montagna Mound, Sicily (Plio-Pleistocene) will be included in this study. By applying microfacies, XRD, stable isotope analyses added by biostratigraphic and ESRdating techniques, a first sequence-stratigraphic model for the deep cold-water carbonate factory will be developed as endproduct.
Recent discoveries of carbonate mounds covered with cold water corals and related benthic communities along the NE Atlantic Ocean continental margin (Porcupine Bight and north of Porcupine Bank, southeast and southwest Rockall Trough Margin, Norwegian Margin) and of actively venting mud volcanic areas along the continental margin surrounding the Gulf of Cadiz associated with authigenic carbonate crust formation and deep-water reef-like coral build-ups and carbonate chimneys margin, Galicia Bank as well as new discoveries of fossil and recent reef structures in the Mediterranean, raises the question of their origin and development. A major objective of the proposed studies therefore is to establish the forcing conditions of carbonate mound formation and to test the hypothesis of a possible linkage between cold seeps and the development of carbonate mounds, cold water benthic communities and authigenic carbonate formation. This proposal is further directed towards a definition of the geological, geochemical and oceanographical conditions and processes forcing the development of carbonate mounds and establishing the benthic ecology and environmental conditions of carbonate mound and cold water coral reef formation in contrasting areas of the NE Atlantic Ocean and Mediterranean Sea. A third objective is to establish the factors governing lithification and stabilisation of carbonate mounds, and to use these as modern analogues of fossil carbonate build ups. Comparison between recent and past mound forcing conditions will allow development of a model of mound genesis in relation to tectonic, sedimentological, oceanographical and biological extant conditions.