Geomorphology of the Australian margin and adjacent seafloor

For the first time, the distribution of seafloor geomorphic features has been systematically mapped over much of the Australian margin and adjacent seafloor. Each of 21 feature types was identified using a new, 250 m spatial resolution bathymetry model and supporting literature. The total area mapped was >8.9 million km2 and included the seafloor surrounding the Australian mainland and island territories of Christmas, Cocos (Keeling), Macquarie and Norfolk Islands. Of this total mapped area, the shelf is >1.9 million km2 (21.92%), the slope >4.0 million km2 (44.80%) and the abyssal plain/deep ocean floor >2.8 million km2 (32.20%). The rise covers 97 070 km2 or 1.08% of the mapped area. A total of 6702 individual geomorphic features were mapped. Plateaus have the largest surface area and cover 1.49 million km2 or 16.54%, followed by basins (714 000 km2; 7.98%), and terraces (577 700 km2; 6.44%), with the remaining 14 types each making up <5%. Reefs, which total 4172 individual features (47 900 km2; 0.54%), are the most numerous type of geomorphic feature, principally due to the large number of individual coral reefs of the Great Barrier Reef. The geomorphology of the margin is most complex where marginal plateaus, terraces, trench/troughs and submarine canyons are present. Comparison with global seafloor geomorphology indicates that the Australian margin is relatively under-represented in shelf and rise and over-represented in slope area, a pattern that reflects the mainland being bounded on three sides by rifted continent – ocean margins and associated large marginal plateaus. Significantly, marginal plateaus on the Australian margin cover 20% of the total world area of marginal plateaus. The mapped area can be divided into 10 geomorphic regions by quantifying regional differences in diagnostic assemblages of features, and these regions can be used as a starting-point to infer broad-scale seafloor habitat types. The present study has application for the future management of Australia's ocean resources.

[1]  N. James,et al.  Bryozoans as carbonate sediment producers on the cool-water Lacepede Shelf, southern Australia , 1993 .

[2]  B. Todd,et al.  The multiple roles of acoustic mapping in integrated ocean management, Canadian Atlantic continental margin , 2003 .

[3]  R. Dietz,et al.  Sedimentation and structure of the continental margin in the vicinity of the Otway Basin, southern Australia , 1970 .

[4]  Suzette V. Suarez.  The Commission on the Limits of the Continental Shelf , 2008 .

[5]  D. Belton,et al.  Sedimentology of the South Tasman Rise, south of Tasmania, from 'groundtruthed' acoustic facies mapping , 1997 .

[6]  M. McCulloch,et al.  Dampier Ridge, Tasman Sea, as a stranded continental fragment∗ , 1994 .

[7]  L. Collins,et al.  Warm-Water Platform and Cool-Water Shelf Carbonates of the Abrolhos Shelf, Southwest Australia , 1997 .

[8]  P. Pirazzoli.  Geomorphology of the Great Barrier Reef , 2008 .

[9]  C. V. D. Borch.  Southern Australian submarine canyons: Their distribution and ages , 1968 .

[10]  Deidre Sullivan,et al.  A classification scheme for deep seafloor habitats , 1999 .

[11]  R. McCauley,et al.  Thermal structure above the Perth Canyon reveals Leeuwin Current, undercurrent and weather influences and the potential for upwelling. , 2006 .

[12]  Rudy J. Kloser,et al.  Seafloor habitat definition for spatial management in fisheries: A case study on the continental she , 1999 .

[13]  M. Younis,et al.  Development and management of a network of marine protected areas in the Red Sea and Gulf of Aden region , 2003 .

[14]  I. Lavering.  Marine environments of Southeast Australia (Gippsland Shelf and Bass Strait) and the impact of offshore petroleum exploration and production activity , 1994 .

[15]  J. Veevers,et al.  Physiography of the Exmouth and Scott Plateaus, Western Australia, and adjacent northeast Wharton Basin , 1974 .

[16]  C. Heine,et al.  Kenn Plateau off northeast Australia: a continental fragment in the southwest Pacific jigsaw , 2006 .

[17]  G. Ashley,et al.  Classification of large-scale subaqueous bedforms; a new look at an old problem , 1990 .

[18]  Peter J. Davies,et al.  The Evolution of the Carbonate Platforms of Northeast Australia , 1989 .

[19]  D. Feary,et al.  Holocene carbonate sedimentation on the west Eucla Shelf, Great Australian Bight: a shaved shelf , 1994 .

[20]  Paul T. Gayes,et al.  Spatially quantitative seafloor habitat mapping: example from the northern South Carolina inner continental shelf , 2004 .

[21]  P. Harris,et al.  Submerged coral reefs in the Gulf of Carpentaria, Australia , 2004 .

[22]  Charitha Pattiaratchi,et al.  Hydrodynamic and sand-transport controls on en echelon sandbank formation: an example from Moreton Bay, eastern Australia , 2002 .

[23]  A. Chivas,et al.  Late quaternary environments of the Carpentaria Basin, Australia , 1988 .

[24]  A. Crawford,et al.  Geological evolution of the East Tasman Plateau, a continental fragment southeast of Tasmania , 1997 .

[25]  J. Royer,et al.  Swath-mapping the Australian continental margin: results from offshore Tasmania , 1995 .

[26]  G. Fader,et al.  Benthic habitat mapping on the Scotian Shelf based on multibeam bathymetry, surficial geology and sea floor photographs , 2001 .

[27]  C. Wilson,et al.  Surficial cool-water carbonate sediments on the Otway continental margin, southeastern Australia , 1993 .

[28]  P. Conaghan,et al.  Phanerozoic earth history of Australia , 1986 .

[29]  T. H. Andel,et al.  Morphology and sediments of the Timor Sea , 1954 .

[30]  R. Duncan,et al.  Age progressive volcanism in the Tasmantid Seamounts , 1988 .

[31]  P. Harris.  Comparison of tropical, carbonate and temperate, siliciclastic tidally dominated sedimentary deposits: Examples from the Australian continental shelf , 1994 .

[32]  M. Wallace,et al.  Pliocene – Pleistocene history of the Gippsland Basin outer shelf and canyon heads, southeast Australia , 2007 .

[33]  Mark E. Taylor,et al.  National frameworks for marine conservation — a hierarchical geophysical approach , 2000 .

[34]  H. Nix,et al.  General bathymetry of the Gulf of Carpentaria and the Quaternary physiography of Lake Carpentaria , 1983 .

[35]  J. Royer,et al.  Plate‐tectonic setting of the Tasmanian region , 1997 .

[36]  P. Harris.  Reversal of subtidal dune asymmetries caused by seasonally reversing wind-driven currents in Torres Strait, northeastern Australia , 1991 .

[37]  R. Müller,et al.  Evolution of the Louisiade triple junction , 1999 .

[38]  L. Collins.  Tertiary Foundations and Quaternary Evolution of Coral Reef Systems of Australia's North West Shelf , 2002 .

[39]  C. Hillenbrand,et al.  Late Quaternary terrigenous sediments from the Murray Canyons area, offshore South Australia and their implications for sea level change, palaeoclimate and palaeodrainage of the Murray–Darling Basin , 2004 .

[40]  T. K. Kyser,et al.  Surficial Sediments of the Great Australian Bight: Facies Dynamics and Oceanography on a Vast Cool-Water Carbonate Shelf , 2001 .

[41]  P. Deckker,et al.  Geomorphology and evolution of the gigantic Murray canyons on the Australian southern margin , 2005 .

[42]  M. Jones,et al.  Late Quaternary evolution of Lake Carpentaria on the Australia‐New Guinea continental shelf , 1988 .

[43]  C. Frohlich,et al.  Neotectonics of the Macquarie Ridge Complex, Australia‐Pacific plate boundary , 2000 .

[44]  J. Conolly.  Submarine canyons of the continental margin, east Bass Strait (Australia) , 1968 .

[45]  C. V. D. Borch.  Marginal plateaus: Their relationship to continental shelf sedimentary basins in Southern Australia , 1967 .

[46]  R. Sprigg.  Submarine canyons of the New Guinea and South Australian coasts , 1947 .

[47]  G R Heath,et al.  Marine geology. , 1982, Science.

[48]  A. Post,et al.  Nature and origin of the submarine Albany canyons off southwest Australia , 2005 .

[49]  T. G. Whiteway,et al.  Australian Bathymetry and Topography Grid , 2009 .

[50]  M. Spalding,et al.  New estimates of global and regional coral reef areas , 1997, Coral Reefs.