Submarine Landslides and Incised Canyons of the Southeast Queensland Continental Margin

An investigation conducted aboard the RV Southern Surveyor (SS2013-V01) in January 2013 offshore east Australia collected regional bathymetric data for the continental margin of southern Queensland between Noosa Heads in the south and Indian Head, Fraser Island in the north. This newly mapped area presents a particularly steep portion of continental slope (5–10°) that presents numerous submarine landslides, including two ‘whole-of-slope’ features (the Wide Bay Canyon, and Inskip Slides). The slope is also dissected by three large submarine canyons offshore northern Fraser Island, Wide Bay, and Noosa Heads (i.e. the Fraser Canyons, the Wide Bay Canyon and the Noosa Canyon). Dredge and core samples were collected from slide scars in the northern, central, and southern areas of the bathymetric survey area. The initial examination of the area’s bathymetry, the core and dredge sample sedimentology, and determination of biostratigraphic ages for these sediment samples indicates that the larger submarine slides present in this study area have probably been shed from the slope since the late Pliocene and that canyon incision is currently active on this portion of the slope. In one case, canyon incision is partly responsible for generating slides due to undercutting and removal of the toe of the slope. Slope sediments are dominantly comprised of hemipelagic muds but also include grain-flows and turbidites comprised of shelf-derived sands and upper slope sediment that have abraided the slope muds. The results confirm previous work that indicates that this margin is in an active phase of deconstruction dominated by mass failure.