Initiation and evolution of an isolated submarine canyon system on a low-gradient continental slope

Li, Wei, Li, Shuang, Alves, Tiago M. ORCID: https://orcid.org/0000-0002-2765-3760, Jing, Song, Chen, Hongjun and Zhan, Wenhuan 2023. Initiation and evolution of an isolated submarine canyon system on a low-gradient continental slope. Geomorphology 434 , 108746. 10.1016/j.geomorph.2023.108746 Item availability restricted.

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Abstract

Submarine canyons are important conduits transferring large volumes of sediment, nutrients, and pollutants from the continental shelf to deep-water basins. However, the mechanisms initiating submarine canyons and the factors influencing their evolution are still poorly understood. Here, we use multibeam bathymetry and two-dimensional seismic reflection data to investigate the origin and development of a submarine canyon system on the northern South China Sea margin. Our results show a submarine canyon system lying at a water depth of 400–1200 m on a relatively low-gradient (<0.5°), open continental slope. At the bottom of this canyon system, buried canyons undercut a mass-transport complex (MTC 1), whose top surface is early Pliocene in age. No other modern or buried canyons, channels and gullies are observed outside the area spanned by MTC 1. Such an observation demonstrates that pre-existing slide scars can capture gravity flows by providing accommodation space for sediment transported onto the lower continental slope, thus facilitating the development of pre-existing channels above MTCs. Lateral accretion packages identified on the southwest walls of several submarine canyons suggest they migrated northeastward due to the influence of contour currents. In addition, the presence of several basal erosional surfaces and smaller-scale MTCs in the canyons confirms they have undergone multiple cut-and-fill cycles, which were likely controlled by relative sea-level changes. The relative high sea level recorded at present ultimately led to the preservation of the studied canyon system on the continental slope. The results not only demonstrate the crucial role of submarine landslides in the initiation of submarine canyons, but also highlight how relative changes in sea level influence the evolution of submarine canyons on low-gradient continental slopes.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Publisher:	Elsevier
ISSN:	0169-555X
Date of First Compliant Deposit:	22 May 2023
Date of Acceptance:	16 May 2023
Last Modified:	29 Jun 2023 21:32
URI:	https://orca.cardiff.ac.uk/id/eprint/159791

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