Influence of bottom currents on the sedimentary processes at the western tip of the Gulf of Corinth, Greece

Abstract

We investigated the sedimentary processes that were active during the Holocene in the Gulf of Corinth, using high-resolution seismic reflection profiles and gravity cores. Seismic reflection data clearly show the presence of shallow-water sediment drifts at the western end of the Gulf, close to the Rion sill that links the Gulf to the Ionian Sea. Short cores indicate that drifts are composed of homogenous bioturbated mud in their upper part. The drift deposits flank a wide central area where the seafloor is eroded and where pre-Holocene deposits locally outcrop. The seafloor morphology in this area is marked by furrows oriented in different directions and by a depression attributed to the action of bottom-currents. The magnetic fabric of sediment samples from the drift, shelves, sub-basins and from the basin floor shows a significant anisotropy and a similar orientation of Kmax axes along core. The largest anisotropy (P=1.043±0.007) is observed in the drift and is interpreted as resulting from the action of bottom currents. The similar orientation of Kmax axes in the other cores, collected from areas east of the drifts, suggests that bottom currents also affect sediment deposition in the rest of the study area, even if seismic profiles and core analyses demonstrate that gravitational processes such as submarine landslides and turbidity currents exert the main control on sediment transport and deposition. Average Kmax axes for four cores were reoriented using the declination of the characteristic remanent magnetization. Kmax axes show variable orientations relatively to the slope of the seafloor, between along-slope and roughly parallel to the contour lines.