Dullo, Wolf-Christian

IODP Expedition 307 Scientific Party

Rüggeberg, Andres

English

OceanRep

Geophysical Research Abstracts,Vol. 10, EGU2008-A-08989, 2008SRef-ID: 1607-7962/gra/EGU2008-A-08989EGU General Assembly 2008© Author(s) 2008Cold-water coral mound initiation and earlydevelopment - results of benthic foraminiferalassemblages and grain-size analysisA. Rüggeberg, C. Dullo, and IODP Exp. 307 Scientific PartyLeibniz-Institute for Marine Sciences (IFM-GEOMAR), Wischhofstr. 1-3, D-24148 Kiel,Germany (arueggeberg@ifm-geomar.de / Phone: +49-431-600 2314)Cold-water corals reefs and carbonate mound provinces in the Porcupine Seabight andthe Rockall Trough of the north Atlantic are known since their first discovery in the1990s (Hovland et al., 1994; Henriet et al., 1998; De Mol et al., 2002). These cold-water coral ecosystems build up several 100-m high mound structures. The controllingmechanisms of initial mound growth and development are still under debate but re-cent mound development is dependent on sedimentary, oceanographic and climaticprocesses (De Mol et al., 2002; Freiwald et al., 2002; Rüggeberg et al., 2005, 2007;Dorschel et al., 2005). However, explanations of the origin and evolution of the Porcu-pine mounds revolve around two scenarios that may be expressed as either competingor complementary hypotheses:(1) oceanographic and paleo-environmental conditions control mound initiation andgrowth, and(2) hydrocarbon seepage initiates microbial-induced carbonate formation and indi-rectly fuels coral growth (endogenous control) (Hovland et al., 1998; Henriet et al.,2001).Integrated Ocean Drilling Program (IODP) Expedition 307 was performed to obtainevidence to better understand the origin and evolution of the deepwater carbonatemounds in Porcupine Seabight. Challenger Mound, a carbonate mound structure cov-ered with fossil cold-water coral rubble, was the focal point of scientific drilling duringIODP 307. Our study of benthic foraminiferal assemblages and grain-size distributionon the first five meters of mound initiation also indicates an environmental control oftheir distribution and variability. No indication of hydrocarbon seepage or microbial-induced carbonate formation has been found, which supports the first hypothesis thatcold-water coral distribution and growth is controlled by oceanographic and paleo-environmental conditions. Recent findings of Dullo et al. (EGU2008-A-02458) un-derline that oceanographic/physical boundary conditions are a prerequisite for livingcold-water coral occurrences. This underpins that environmental and oceanographicfactors are controlling mound initiation, at least until more information on moundbases exist.References:De Mol B., Van Rensbergen P., Pillen S., Van Herreweghe K., Van Rooij D., McDon-nell A., Huvenne V., Ivanov M., Swennen R., and Henriet J.-P. (2002) Large deep-water coral banks in the Porcupine Basin, southwest of Ireland. Marine Geology 188,193-231.Dorschel B., Hebbeln D., Rüggeberg A., Dullo W.-Chr., and Freiwald A. (2005)Deglacial sweeping of a deep-water carbonate mound. Earth and Planetary ScienceLetters 233, 33-44.Expedition Scientists, 2005. Modern carbonate mounds: Porcupine drilling. IODPPrel. Rept., 307. doi:10.2204/iodp.pr.307.2005Freiwald A. (2002) Reef-Forming Cold-Water Corals. In Ocean Margin Systems (ed.G. Wefer, D. Billett, D. Hebbeln, B. B. Jørgensen, M. Schlüter, and T. v. Weering), pp.365-385. Springer Verlag.Henriet J.-P., De Mol B., Pillen S., Vanneste M., Van Rooij D., Versteeg W., CrokerP.F., Shannon P.M., Unnithan V., Bouriak S., and Chachkine P. (1998) Gas hydratecrystals may help build reefs. Nature 391, 648-649.Henriet J.-P., De Mol B., Vanneste M., Huvenne V., Van Rooij D., and the Porcupine-Belgica 97, 98, and 99 Shipboard Parties (2001) Carbonate mounds and slope failuresin the Porcupine Basin: a de-velopment model involving fluid venting. In: Shannon,P.M., Haughton, P., and Corcoran, D. (eds.) Petroleum Exploration of Ireland’s Off-shore Basins. Geol. Soc. Spec. Publ., 188, 375-383.Hovland M., Croker P.F., and Martin M. (1994) Fault-associated seabed mounds (car-bonate knolls?) off western Ireland and north-west Australia. Mar. Pet. Geol., 11, 232-246. doi:10.1016/0264-8172(94)90099-XHovland M., Mortensen P. B., Brattegard T., Strass P., and Rokengen K. (1998) Aher-matypic coral banks off mid-Norway: evidence for a link with seepage of light hydro-carbons. Palaios, 13, 189-200.Rüggeberg A., Dullo C., Dorschel B., and Hebbeln D. (2007) Environmentalchanges and growth history of Propeller Mound, Porcupine Seabight: Evidence frombenthic foraminiferal assemblages. International Journal of Earth Sciences, DOI:10.1007/s00531-005-0504-1.Rüggeberg A., Dorschel B., Dullo W.-Chr., and Hebbeln D. (2005) Sedimentary pat-terns in the vicinity of a carbonate mound in the Hovland Mound province, northernPorcupine Seabight. In: A. Freiwald and J.M. Roberts (eds.) Cold-water Corals andEcosystems. Springer-Verlag Berlin Heidelberg, pp 87-112.

Cold-water coral mound initiation and early development - results from benthic foraminiferal assemblages and grain-size analysis

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