Geomorphological development of the Goto Submarine Canyon, northeastern East China Sea

Abstract

The geomorphological development of submarine canyons is controlled by multiple factors, such as sea-level fluctuations, tectonic activity, and ocean currents, but the relative contributions of each factor vary among these canyons. The development of submarine canyons along active rift margins is not fully understood because there are relatively few documented examples of such phenomena. The Goto Submarine Canyon offers a good example of this type of structure because it is located on the flank of the Okinawa Trough, which is an active back-arc basin. Through multi-beam bathymetry, multi-channel seismic reflection profiling, and remotely operated vehicle surveys, we reveal that this canyon is more than four times wider than other submarine canyons and has a gradient that is half as deep and a remarkably flat canyon floor. A series of upstream-facing cliffs with reliefs up to 110 m and longitudinal lineaments are also associated with this canyon. These morphological features can mainly be attributed to direct sediment inputs from the Yellow River during glacial stages, vertical incision prevented by erosion-resistant beds, and faulting and tectonic tilting of resistant strata. The possibility of tidal current-induced erosion is also suggested. These processes have been influenced primarily by regional factors, such as the wide continental shelf, carbonate cementation, and active rifting of the Okinawa Trough. The contribution of rifting, including faults and tectonic tilting, to the canyon's morphology is expected to be a general characteristic of submarine canyons along active rifting margins.