Seismic geomorphological analysis of deepwater gravity-driven deposits on a slope system of the southern Colombian Caribbean margin |
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| Institution: | 1. Instituto de Geociências, Programa de Pós-graduação em Geofísica, Universidade Federal da Bahia, Salvador, Bahia, Brazil;2. Instituto de Geociências, Universidade Federal da Bahia, Salvador, Bahia, Brazil;1. Department of Earth Sciences and Engineering, Imperial College London, UK;2. BP, Chertsey Road, Sunbury-on-Thames, Middlesex, TW16 7BP, UK;1. Research Institute of Exploration and Development, PetroChina Jidong Oilfield, Hebei, Tangshan, 063004, China;2. Sinopec Petroleum Exploration and Production Research Institute, Beijing, 100083, China;3. Hubei Cooperative Innovation Center of Unconventional Oil and Gas (Yangtze University), Wuhan, Hubei, 430100, China;4. Laboratory of Exploration Technologies for Oil and Gas Resources (Yangtze University), Ministry of Education, Wuhan, Hubei, 430100, China;1. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;2. College of Earth Sciences, Jilin University, Changchun 130061, China;3. SINOPEC Northeast Petroleum Bureau, Changchun 130056, China;4. Department of Earth Sciences, University of Toronto, Toronto M5S 3B1, Canada;5. Research Institute of Exploration and Development, Daqing Oilfield Limited Company, Daqing 163712, China;6. Research Institute of Petroleum Exploration and Development, CNPC, Beijing 100083, China;1. Université Toulouse 3, Paul Sabatier, Géosciences Environnement Toulouse, 14 avenue Edouard Belin, 31400, Toulouse, France;2. School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester M13 9PL, UK;3. Department of Geology and Geophysics and Coastal Studies Institute, E235 Howe-Russell, Louisiana State University, Baton Rouge, Louisiana 70803, USA |
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| Abstract: | Gravity-driven processes are important agents for transporting sediments downslope into deep-marine environments. The Pliocene to Holocene offshore succession of the Colombian Caribbean margin and its stratigraphic distribution, have been affected by faulting and mud diapirism, and have been characterized using 3D seismic data. Nine stratigraphic intervals were characterized within the study, and are interpreted to consist of a range of seismic geomorphologies, including slumps and debrites. Nine gravity-driven deposits were defined within the study area, interpreted to have been transported to the north and northwest. Slumps display high-amplitude, high continuity, elongated, stratified, lobate and confined morphologies, while debrites have a reflection-free pattern or show discontinuous, low-amplitude and chaotic reflections. Mixed slumps-turbidites-debrites deposits are composed by a succession of laterally and vertically interfingered slumps, debrites and turbidites. These deposits are morphologically lobate and broadly scattered. In addition, erosional features such as basal small scours, megascours, linear scours and rafted blocks were used as kinematic indicators within the gravity-driven deposits. There are several candidates triggering mechanism, including over-steepening of slope (related to high sediment supply or slope tectonism). In the study area, confined slumps and debrites with a main transport direction from south to north have been observed, while transport direction of the mixed slumps-turbidites-debrites was toward northwest. Additionally, the fact that slumps and debrites are found in depocenters between periclines suggests a confined environment of deposition. Finally, mixed slumps-turbidites-debrites are unconfined without evident structural control. We suggest that local intraslope sub-basin margin become over-steepened as a result of mud diapirism in the subsurface. In this situation, the paleobathymetry was sufficient to trap the resultant gravity-driven deposits within the sub-basins, suggesting a local origin. Seismic evidence of BSR (Bottom Simulating Reflector) suggests the presence of gas hydrate in the study area, and is taken as an additional potential mechanism to provide instability of slope and generate gravity-driven deposits. |
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| Keywords: | Caribbean margin Seismic attributes Seismic geomorphology Mass-transport deposits Deepwater deposits Diapirs |
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