Fields of multi-kilometer scale sub-circular depressions in the Carnegie Ridge sedimentary blanket: Effect of underwater carbonate dissolution? |
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| Institution: | 1. ISMAR-CNR, UOS Bologna, Via Gobetti 101, 40129 Bologna, Italy;2. Woods Hole Oceanographic Institution, 266 Woods Hole Rd, Woods Hole, MA 02543, USA;3. Abteilung Meeresforschung, Senckenberg am Meer, Südstrand 40, D-26382 Wilhelmshaven, Germany;4. ISPRA, Via Brancati 48, 00144 Rome, Italy;5. Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA;6. Laboratoire des Sciences du Climat et de l''Environnement, Laboratoire mixte CNRS-CEA, Av. de la Terrasse, 91198 Gif-sur-Yvette, France;7. ISMAR-CNR Headquarters, Arsenale Tesa 104, Castello 2737/F, Venice, Italy;1. IRD-Sorbonne Universités (UPMC, Univ Paris 06)-CNRS-MNHN, LOCEAN Laboratory, IRD France-Nord, 32, avenue Henri Varagnat, F-93143 Bondy, France;2. UMR PALOC, IRD/Museum National d''Histoire Naturelle, 57 rue Cuvier, CP 26, 75231 Paris cedex 05, France;1. KU Leuven, Geology, Department of Earth and Environmental Sciences, Celestijnenlaan 200E, 3001 Heverlee, Belgium;2. UMONS, University of Mons, Faculty of Engineering, Mining Engineering Department, Place du Parc 20, 7000 Mons, Belgium |
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| Abstract: | Offshore Ecuador, the Carnegie Ridge is a volcanic ridge with a carbonate sediment drape. During the SALIERI Cruise, multibeam bathymetry was collected across Carnegie Ridge with the Simrad EM120 of the R/V SONNE. The most conspicuous features discovered on the Carnegie Ridge are fields of circular closed depressions widely distributed along the mid-slope of the northern and southern flanks of the ridge between 1500 and 2600 m water depth. These circular depressions are 1–4 km wide and typically 100–400 m deep. Most are flat floored and some are so densely packed that they form a honeycomb pattern. The depressions were carved into the ridge sedimentary blanket, which consists of carbonate sediment and has been dated from upper Miocene to upper Pleistocene. Several hypotheses including pockmark origin, sediment creeping, paleo-topography of the volcanic basement, effects of subbottom currents, and both marine and subaerial karstic origins are discussed. We believe that underwater dissolution process merits the most serious consideration regarding the origin of the closed depression. |
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