Complex seabed geomorphology shaped by various oceanographic processes: a case study from the Gippsland Basin, offshore south-eastern Australia

Abstract

The Gippsland Basin is located in the south-eastern continental margin of Australia and hosts a variety of important marine resources (i.e. hydrocarbons, offshore wind, biological diversity, and fishing resources). Recent high-resolution seabed mapping reveals a complex seabed morphology in the Gippsland Basin, containing scarps, cyclic steps, channels, canyons, gullies, and giant submarine landslides. However, previous studies have not yet revealed the dominant sedimentary processes behind this morphological complexity. We combine high-resolution multibeam bathymetric and seismic reflection datasets to investigate the dominant sedimentary processes that are active in shaping these complex seabed morphologies. In the northern region of the study area, slope failures are prevalent on the shelf and slope, which are primed by the deposition of contourites generated by the East Australian Current. In the central and southern regions, the Bass Cascade Current can carry large amounts of sediments, scouring the shelf and slope, and can form supercritical turbidity currents that create a variety of erosional seabed morphologies. We suggest that slope gradient variation, oceanography and a variety of sedimentary processes jointly contributed to the seabed morphological complexity in the Gippsland Basin. The high-resolution seabed morphological analysis within this study provides critical geomorphological and geological information for future submarine constructions (i.e. locating potential wind farms and telecommunication cable installations) along with geohazard prediction and mitigation (i.e. knowing the location of past and predicting future giant landslides).