Slope-confined submarine canyons in the Baiyun deep-water area, northern South China Sea: variation in their modern morp
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ORIGINAL RESEARCH PAPER
Slope-confined submarine canyons in the Baiyun deep-water area, northern South China Sea: variation in their modern morphology X. S. Li1,2 • Q. J. Zhou1 • T. Y. Su1 • L. J. Liu1,2 • S. Gao1 • S. W. Zhou3
Received: 30 November 2015 / Accepted: 23 April 2016 Springer Science+Business Media Dordrecht 2016
Abstract On the basis of newly collected multibeam bathymetric data, chirp profiles and existing seismic data, we presented a detailed morphological interpretation of a series of slope-confined canyons in water depths of 300–2000 m in the Baiyun deep-water area, northern margin of the South China Sea. Although these canyons are commonly characterized by regular spacing and a straightline shape, they vary in their lengths, starting and ending water depths, canyon relief, slope gradients, wall slope gradients and depth profiles along the axis. The eastern canyons (C1–C8) have complex surface features, low values in their slope gradient, canyon relief and wall slope gradient and high values in their length and starting and ending depth contrasting to the western ones (C9–C17). From the bathymetric data and chirp profiles, we interpret two main processes that have controlled the morphology and evolution of the canyons: axial incision and landsliding. The western part of the shelf margin where there were at least four stages of submerged reefs differs from the eastern part of the shelf margin where sedimentary undulations occurred at a water depth of *650 m. We consider that the variation in morphology of submarine canyons in the study area is the result of multiple causes, with the
& X. S. Li [email protected] 1
Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, State Oceanic Administration, 6 Xianxialing Road, Qingdao 266061, China
2
Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
3
The Survey Center of China Oilfield Services Limited, Tianjin, China
leading cause being the difference in stability of the upper slope which is related to the submerged reefs and sedimentary undulations. Keywords Submarine canyon Morphology Submerged reefs Undulated structure North of South China Sea
Introduction Slope-confined canyons are complex features that develop along the continental slope and are distinguished from other submarine canyons in being detached from the shelf and the subaerial river system (Twichell and Roberts 1982; Bertoni and Cartwright 2005; Brothers et al. 2013). They are widespread along most continental margins of the world (Twichell and Roberts 1982; David and David 1982; O’Connell et al. 1987; Alonso et al. 1991; McAdoo et al. 1997; Canals et al. 2000; Bertoni and Cartwright 2005; Harris and Whiteway 2011; Mulder et al. 2012; Huang et al. 2014) and act as conduits for transporting sediments (Shepard 1963; Normark 1974; Forde et al. 1981; Normark et al. 2009; Allen and Durieu de Madron 2009) and traps for turbidite sands as oil and gas reservoirs (Hardage
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