AUSCAN Seafloor Mapping and Geological Sampling Survey on the Australian Southern Margin by RV Marion Dufresne in 2003: Final Project Report

AUSCAN (Australian Canyons), a major research expedition that investigated Australia's southern margin from southern Tasmania in the east to off Cape Leeuwin in the west, successfully completed its mission in March 2003. The investigation included multibeam swath-mapping, geophysical profiling, geological and biological sampling, as well as oceanographic measurements. The data were collected to support marine environmental planning and management, to help model the structural and sedimentological evolution of the margin, and to assist understanding the climatic, oceanographic and environmental changes that affected the region during the late Quaternary. Important objectives were to map in detail and study the geomorphology and origins of the gigantic, but poorly known, canyon systems that exist beyond the continental shelf. The spectacular Murray Canyons south of Kangaroo Island, with their complex and extensive channel systems and 2-km high cliffs, were a special focus of the investigation. The information collected and resulting research will assist implementation of Australia's Oceans Policy and Australia's Marine Science and Technology Plan, and in particular, the development of the South-east Regional Marine Plan by the National Oceans Office. The new data, integrated with the pre-existing seabed data sets, provide the basis for environmental management strategies and plans, and also provide framework information to support future biological and physical scientific field studies and research. AUSCAN was completed as two cruise legs totalling 3 weeks using the 120-m R/V Marion Dufresne of the French Polar Institute (IPEV). The survey used a range of geophysical, sampling and oceanographic equipment carried on the ship, but vital to the AUSCAN program were the ship's Thales Sea Falcon 11 multibeam sonar swath-mapper and its giant piston corer, Calypso?. The multibeam system produces high-resolution bathymetric and backscatter images of the sea floor at 15 knots across a swath up to 20 km wide in deep water, whileCalypso' is capable of recovering deepsea sediment cores up to 60 m long. The cruise was based on excellent international scientific cooperation, and included scientists from Australia, France, Germany, other European countries, and the USA. IPEV was the main French organisation involved, while Australian institutions included Geoscience Australia (GA), the Australian National University, SARDI (South Australian Research & Development Institute) and the National Oceans Office (NOO). CSIRO Marine Research (Hobart) also provided input during the planning phase. NOO provided much of the Australian funding and support because of AUSCAN's direct and important relevance to current regional marine planning and environmental management initiatives, including development of National Bioregionalisation and the South-east Regional Marine Plan. GA managed the project for NOO. The AUSCAN program was designed to build on earlier major swath-mapping surveys involving French-Australian cooperation (GA and IPEV/IFREMER), such as TASMANTE off west Tasmania and on the South Tasman Rise, MARGAU off southwest Western Australia, and AUSTREA-1 off southeast and southern Australia. AUSCAN swath-mapped 70,000 km of seabed (about the size of Tasmania), filling many of the existing data gaps along the southern margin and now allowing detailed maps and images of almost the entire continental slope from Western Australia to Tasmania to be produced for the first time. AUSCAN also acquired 3.5 kHz sub-bottom profiler, gravity, magnetics and oceanographic data along 9,000 km of survey line.