Acoustic structure and recent sediment transport processes on the continental slope of Yeşilırmak River fan, Eastern Black Sea

High-resolution acoustic data indicate that sediment erosion is a significant process in the continental slope of Yeşilırmak River Fan, occurring both related to the submarine canyons and in the open continental slope. The sediment processes observed along the slope consist of sliding and debris flows on the canyon walls together with the recent erosional surfaces at the canyon heads wherever the canyons exist, and slides and related scarp features structurally controlled by rotational faults in the central part of the open continental slope.Formation of slides both on the open slope and in canyon walls is a multi-phase sliding process, in which successive sliding events occur at the same location producing a vertically stacked sliding, resulting in several relict slide features deeper parts in the sediments. We conclude that gravitational loading on the steep slope is the main driving force for most of the erosional features, and in place to place, overpressured pore fluids due to gas accumulation can contribute the instability.Tributary canyon systems are observed on the slope, with slide scars in the proximal part. According to their different erosional structure, these canyons can be separated into two groups, as northern and southern sector canyon systems, where the sediment bypass and hence erosional processes are much more active on the canyon heads in the southern sector than those in the northern part. Terrigenous sediment load from Yeşilırmak River is transported along downslope by successive hyperpycnal fluxes and the activity of turbidity currents along the channel axis.Acoustic data indicate that the continental slope of Yeşilırmak River Fan is a classical deep-sea turbidite system, where we observe slide scars in proximal part, and channel levee systems with slide and debris flow deposits inside the channels in the distal part with some small sized gullies.