NEW INSIGHTS INTO PROCESSES INFLUENCING SUBMARINE GULLY MORPHOLOGY FROM HIGH-RESOLUTION MARINE ROBOTICS (Invited Presentation)

Submarine gullies are pervasive features of continental margins and are thought to be the first features to develop on continental slopes. They influence sediment transport and deposition down-slope, have a key role in continental margin evolution and are pathways for sediment deposits on the continental slope and rise. Gullies occur on both active and passive margins, on submarine volcanic slopes, deep-sea sediment drifts, and ocean ridges and persistently across all latitudes. Some show striking similarities to their sub-aerial and Martian counterparts. The processes influencing submarine gully morphology remain poorly constrained because of inaccessibility, with suggested mechanisms including turbidity currents, debris flows, slides, slumps and oceanographic processes such as dense water overflows and contour currents. Here, we identify distinct gully types from quantitative analysis of geophysical data and attempt to link morphology with formation mechanisms. This includes data collected by a fleet of marine robots, providing cm-scale resolution geophysical data, targeted sediment cores from gully flanks and axes, and in-situ video footage showing fine-scale gully-morphology. We infer that processes influencing gully morphology vary with local slope character and regional factors such as presence of fans, sediment type and yield, and environmental setting. Analysis of gully morphometric parameters and spatial distribution patterns together with environmental derived parameters, such as slope gradient and geometry, provide a step forward in constraining processes operating on continental margins and environmental controls influencing gully morphology. We show that gullies are fundamental in contributing to the evolution of continental margins, are active systems today and highlight their importance compared to well-documented down-slope processes.