Depositional characteristics and spatial distribution of deep-water sedimentary systems on the northwestern middle-lower
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ORIGINAL RESEARCH PAPER
Depositional characteristics and spatial distribution of deep-water sedimentary systems on the northwestern middle-lower slope of the Northwest Sub-Basin, South China Sea Hui Chen • Xinong Xie • David Van Rooij • Thomas Vandorpe • Li Huang • Laiyuan Guo Ming Su
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Received: 8 April 2013 / Accepted: 26 August 2013 / Published online: 29 September 2013 Ó Springer Science+Business Media Dordrecht 2013
Abstract Based upon 2D seismic data, this study confirms the presence of a complex deep-water sedimentary system within the Pliocene-Quaternary strata on the northwestern lower slope of the Northwest Sub-Basin, South China Sea. It consists of submarine canyons, masswasting deposits, contourite channels and sheeted drifts. Alongslope aligned erosive features are observed on the eastern upper gentle slopes (\1.2° above 1,500 m), where a V-shaped downslope canyon presents an apparent ENE migration, indicating a related bottom current within the eastward South China Sea Intermediate Water Circulation. Contourite sheeted drifts are also generated on the eastern gentle slopes (*1.5° in average), below 2,100 m water depth though, referring to a wide unfocused bottom current, which might be related to the South China Sea Deep Water Circulation. Mass wasting deposits (predominantly slides and slumps) and submarine canyons developed on steeper slopes ([2°), where weaker alongslope currents are
probably dominated by downslope depositional processes on these unstable slopes. The NNW–SSE oriented slope morphology changes from a three-stepped terraced outline (I–II–III) east of the investigated area, into a two-stepped terraced (I–II) outline in the middle, and into a unitary steep slope (II) in the west, which is consistent with the slope steepening towards the west. Such morphological changes may have possibly led to a westward simplification of composite deep-water sedimentary systems, from a depositional complex of contourite depositional systems, mass-wasting deposits and canyons, on the one hand, to only sliding and canyon deposits on the other hand. Keywords Deep-water sedimentation Bottom current Contourite Mass-wasting deposits South China Sea
Introduction H. Chen X. Xie (&) L. Huang L. Guo Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, Faculty of Resources, China University of Geosciences, Wuhan 430074, China e-mail: [email protected]; [email protected] H. Chen D. Van Rooij T. Vandorpe Department of Geology and Soil Science, Renard Centre of Marine Geology, Ghent University, Krijgslaan 281 s8, 9000 Ghent, Belgium M. Su Key Laboratory of Renewable Energy and Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China M. Su Guangzhou Center for Gas Hydrate Research, Chinese Academy of Sciences, Guangzhou 510640, China
Deep-water sedimentary systems have been receiving intensive attention from the scientific community during the recent decades, due to their crucial importance for natural resources (e.g., dee
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