Types and processes of sediment dispersal systems across the continental margin: Insights from the northern slope of the South China Sea

The shelf-margin slope area, spanning tens of thousands of kilometers, represents the most dynamic sedimentary zone on Earth’s surface. How sediment is transported from the continental shelf to the deep-water basin has long been a topic of widespread interest, and the driving mechanisms remain controversial. This study takes the shelf margin of the northern South China Sea as an example, based on over ten thousand square kilometers of 3-D seismic data and a few drilling and well-log data, to investigate deep-water sediment dispersal and the driving processes across the shelf margin. The study reveals three major sediment delivery systems, including (1) large-scale slump-channel complexes and coarse-grained slope fan systems at the front of high-angle shelf-edge deltas, (2) canyon-channels and medium- to fine-grained channel-fan complexes along the front of gently sloping shelf-edge deltas and muddy shelf-margin slopes, and (3) unidirectionally migrating valleys and fine-grained slope fan apron systems. The delivery of clastic deposits across the shelf margin has been primarily driven by variations in accommodation (sea-level fall), with the migration of fluvial deltas to the shelf edge, the collapse of the shelf slope, and the incision of slope channels. The instability of high-angle shelf-margin clinoforms and paleogeographic features of the basin are also important constraints.