Gravity-driven sediment transport on continental shelves: A status report |
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| Institution: | 1. Institute of Geology, Adam Mickiewicz University in Poznań, Maków Polnych 16, 61-606 Poznań, Poland;2. MARUM — Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, 28359 Bremen, Germany;3. Institute of Geosciences, University of Kiel, Otto-Hahn-Platz 1, 24118 Kiel, Germany;4. Institute of Geology and Paleontology, Basel University, Bernoullistrasse 32, 4056 Basel, Switzerland;5. Institute of Marine Geology and Geophysics, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Street, Cau Giay District, Hanoi, Viet Nam;1. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China;2. Hydro-environmental Research Centre, School of Engineering, Cardiff University, Cardiff CF24 3AA, UK;1. Antarctic Research Centre, Victoria University of Wellington, Wellington 6012, New Zealand;2. Department of Oceanography, National Sun Yat-sen University, Kaohsiung 80424, Taiwan;3. National Oceanography Centre, European Way, Southampton SO14 37H, UK;4. EGS (Asia) Ltd., 1067 King''s Road, Quarry Bay, Hong Kong;1. Andalusian Institute for Earth System Research, University of Granada, Avda. del Mediterráneo, s/n, 18006 Granada, Spain;2. Department of Aerospace Engineering and Fluid Mechanics, University of Seville, Camino de los Descubrimientos, s/n, 41092 Seville, Spain;3. School of Marine Science and Engineering, Plymouth University, PL4 8AA, Drake Circus, Plymouth, UK |
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| Abstract: | Recent field observations from several shelf environments show that gravity-driven transport within negatively buoyant layers is an important mode of fine sediment transport across continental shelves. Specifically, Dick Sternberg, along with his students and colleagues, stimulated a paradigm shift by reporting strong evidence from the Amazon and Eel shelves that hyperpycnal layers do not require autosuspension for sustenance but can be initiated by sediment flux convergence and supported by wave and current-induced suspension within relatively thin near-bed layers. As these layers move downslope under the influence of gravity, they may deposit sediment in response to decreases in bottom orbital velocities, near-bed current velocity, and/or bed slope. Direct or indirect evidence for wave or current supported sediment gravity flows has recently been reported off other high-load rivers including the Atchafalaya, Fly, Ganges–Brahmaputra, Klamath, Mad, Mississippi, Po, Rhone, Waiapu, Waipaoa, Yangtze, and Yellow among others. Growing evidence from observational and modeling studies suggests that flux convergence followed by wave and current supported gravity driven transport is a primary cause of across-shelf transport and emplacement of flood deposits on many muddy shelves and may be a major contributor to and control on the large-scale formation and morphology of subaqueous deltas and shelf clinoforms. Recent and ongoing studies on this subject are synthesized in this paper and recommendations are offered for further study. |
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