Sediment waves control origins of submarine canyons

Submarine canyons commonly occur on virtually all continental slopes. Their varied origins are widely studied but still debatable. Eastward (along-slope)-migrating submarine canyons, with nearly regular spacing, are well developed at the northern South China Sea. High-resolution three-dimensional seismic data show that these canyons are localized in the troughs between sediment waves. The waves were present on the slope since before ca. 10.5 Ma and were especially well developed during the late Miocene (ca. 10.5-5.5 Ma). This interval can be divided into two units, of which the upper unit (SU II) has larger sediment waves and much better-developed canyons compared to the lower unit (SU I). Submarine fans developed at the canyon mouths within SU II at the downdip termination of the confinement caused by the sediment waves. Gravity currents were captured between the waves, resulting in erosion mainly along the troughs between them. The canyons were forced to migrate eastward by the migration of the confining sediment waves. In this study, we present a new mechanism for the origin of such regularly spaced submarine canyons for the first time, which we at-tribute to the formation of regularly spaced sediment waves generated by contour currents.

Automated summary

Submarine canyons that migrate eastward and have regular spacing are well-developed at the northern South China Sea. The canyons are localized in the troughs between sediment waves and their migration is forced by the migration of the confining sediment waves. This study presents a new mechanism for the origin of such submarine canyons, attributing them to the formation of regularly spaced sediment waves generated by contour currents.