Sediment Transport processes on an active submarine fault escarpment: Gulf of Corinth, Greece

Abstract

Sediment transport processes on the escarpment of a listric fault in the tectonically active and terrigenous sediment-dominated Corinth graben in Greece are studied using 3.5 kHz and airgun profiles and sidescan sonar images. The whole of the slope area is affected by gravitational mass movements: slumps, debris/mud flows and liquified and turbidity flows. In canyon fan systems, large volumes of sediment are transported through slumping, debris/mud and turbidity flows into the basin. Here, they build coalescing fans which consist of intercalations of debris flow deposits and turbidites. In delta front-slope-fan apron systems, sediments are transported radially downslope through slumping, debris/mud flows, liquified flows and high-density turbidity flows into the basin where they build coalescing fan aprons. These consist of massive homogenized deposits (fluxoturbidites). In shelf slope systems retrogressive rotational slumping is the dominant instability feature. However, due to the sharp increase in the slope gradient caused by the slumping, debris and turbidity flows are triggered. The major factors responsible for triggering gravitational mass movements in the region are earthquakes, high sedimentation rates off the river mouths and heavy rainfalls and high seas. These mass movements appear to occur at least once every 2 yrs as indicated by the failure of submarine cables.